I am guessing it might even be something like a short, playable engine demo who's main purpose will be to market Valve's new engine mechanics...and then Valve will promptly go back to not making anymore full Half-Life games.
In fact, I think the only reason why Valve even made Half-Life: Alyx was a glorified tech demo for VR headsets.
Do not get me wrong, Half-Life: Alyx was a good game, but game development is not a very high priority for Valve anymore with the success of the Steam platform.
And I feel like Valve is entering their passion project era. HL2's 20th anniversary documentary basically showed Valve's old guard including Gabe are tired of their money printers and miss the times when they made games. Besides, if Valve was doing another "glorified tech demo" like Alyx to sell hardware, why would they be going above and beyond to hire industry veterans for this project? It's a half-assed tech demo, get a bunch of people they already hired to work on it like they did with Alyx and call it a day, why put so much effort into it?
Not to mention, Half-Life 2 has also been called a "glorified tech demo" for years, yet everyone loved it, everyone loved the episodes, and the reason people are constantly on the edge for the next Half-Life games is because of the cancelled Episode 3. Clearly that's what people want, so it's idiotic to keep bringing it up as a criticism against Half-Life. Just look at the reactions to the development footage of Episode 3 with the ice gun and the blob enemy, people want tech demo gimmicks like that, because they're interesting, they're fun. If they weren't, Half-Life 2 would've flopped those two decades back.
HLX is shaping up to be Valve's RDR2, a game that Valve always wanted to do, and now that they have fuck you money, they can. My expectations is that it will be "HL3" in everything but the name. It will pick up from the end of HL:A with Gordon as the protagonist, will continue his journey towards the Borealis, and it will very likely be designed to be both playable with mouse and keyboard as well as VR headsets. Obviously it won't be what people wanted for all these 17 years, but it will be damn good enough. Valve will explicitly avoid calling it a "HL3" due to what I already said, but people will see it as a "HL3" once they play it, and that will be the best outcome. Everyone already calls it that so it's best to not pour more gasoline onto the fire, HLX it is, let people speculate if it's gonna be HL3 or not, if they overhype themselves too hard, it's on them, there's nothing Valve could do to not let that happen.
I give Valve the benefit of the doubt. I get that everyone took the /v/ poison pill of "everything sucks and nothing gets better", but Valve isn't Ubisoft or EA. The stockholders they are meant to appease are their own employees, not some senile schmuck in a suit that only cares to see a green line go up every quarter. They're not enslaved to stagnation of perpetually making safe profits, they got the freedom to take risks and innovate. They've proven to still have plenty of creative talent that's able to deliver a quality product, and most importantly, they still show that they can learn from their mistakes.
And if you take a retrospect on what Valve was doing up until this point, it's clear they've made all the mistakes needed to make a comeback. A huge, proper comeback.
2011-2015 was the era of stagnation for Valve. Portal 2 was released, then a year later, CS:GO. The Steam money printer worked perfectly, from the storefront to the microtransaction market. It was also the time when their flat management structure was in full swing, which led to nothing being done and talent like Laidlaw leaving in droves. In 2015, Valve did their first ventures into hardware, all three failed for various reasons, and set the expectation that Valve is incapable of delivering good hardware, ever. Steam Machines were overpriced for what they offered, Steam Controller was a good, but ultimately flawed attempt at making a controller for PC games, and the Steam Link got replaced by an app for Android TV.
Later on they've collabed with HTC to developed the Vive, and when they started working on Alyx circa 2016, that's when they realized their flat structure needed to be scrapped, it's time to make a project, get people to work on it, and bring it to fruition. Get shit done. Took them long enough to learn from that mistake but better late than never. Then in 2019, Valve Index happened. Valve learned from working with HTC and working on Alyx enough to come up with their own VR headset which was quite revolutionary with it's finger tracking. Obviously Facebook beat them to the punch in regards to VR tracking technology months before the release of the Index, and by the very nature of VR headsets, people could only see the negatives, that it's an expensive gimmick, that Valve can't make hardware and so on. They'll never learn.
But then the Steam Deck happened in 2022, which was essentially a culmination of Valve's learning from mistakes process. They reiterated on the Steam Controller concept, they've realized that VR is too much of a niche and expensive gimmick to easily catch on, and that there is a market void for PC handhelds that was only partially filled by GPD. Once the Deck came out, it became their biggest hardware success yet. Valve took a major risk no other company was willing to make, and it paid off big time, so much so that stockholders of all the publicly traded companies now told them to make a "Steam Deck killer" with all the obvious signs of playing it safe and missing the point of why the Deck was a success, from reliance on Windows to keeping the Xbox control scheme, since it's the least risky one to use for making the green line go up.
Meanwhile the two halves of what made Deck a success is the custom Linux distribution designed for the Deck, giving it a proper, smooth handheld console experience without it feeling like a janky workaround on a OS that was never designed for this unique form factor, and most importantly, the control scheme. Valve took your usual console controller, decided that neither the Playstation/Wii U Pro symmetrical layout, nor the Xbox/Gamecube/Switch asymmetrical layout was a good option, because what makes real sense is putting the analog sticks and the D-pad/action buttons in one line. Then for those extra PC controls, two haptic touchpads, gyro controls, four rear buttons. Boom, instant hit, it's the Steam Controller but not crippled.


And clearly, once again, Valve has learned from their mistakes. The upcoming Steam Controller 2 is what people have wanted, essentially a screenless Deck.
Remember how people declared Valve is incapable of designing hardware back in 2015 when the first Steam Controller was released? Well here we are now, it took Valve a few good years of trial and error, but they've finally figured out how to design a proper controller, despite everyone saying they can't.
Because they've learned from their mistakes. To say that HLX will be a tech demo to sell VR headsets like HL:A is gullible and shortsighted, Valve is smarter than that.
This is why I believe in them delivering on everything they have in works. They will learn from HL:A that people want a Half-Life game that won't be locked to an expensive gizmo, so you will be able to play it on a PC, on a Steam Deck, and with a VR headset if you so desire, it will be a proper game this time. They will learn from the Index, and the upcoming 'Deckard' VR headset w/ 'Roy' controllers will be self-tracking like the Quest, and also priced competitively to it, possibly well enough that people will be more willing to delve into the world of VR games. They will learn from the Steam Machines and the 'Fretmont' console will be a proper living room PC console people will find value in.
And since they've already learned from the Steam Controller, the upcoming 'Ibex' controller will be a no-brainer buy for any PC gamer. I know I'll be looking forward to it, out of all the projects they have in the works, this is the one I'm excited about the most.