I'm doubtful that we're going to get a successor to GX, but not because of financial reasons.
I think its a mix of financial and no one wanting to take on the IP for Nintendo. If SEGA came in and pitched a new one, they would most likely allow it, otherwise, Nintendo really has no incentive to. The games were never major sellers past the original, so any attempt to reignite the series will be based purely on another's willingness to give it another round.
This mentality tracks with Nintendo's current strategy when it comes to their bizarre revivals. Most have had another dev come in for them.
- Advanced Wars - WayForward
- Endless Ocean - Arika (same devs as original, but back to try and do an asset flip of a mobile title)
- Another Code - Arc System Works
- Famicon Detective Club - MAGES
Nintendo has atm when you also point out how Nintendo made new entries in Advanced Wars, Another Code, Endless Ocean, Clubhouse 51, and Famicam Detective Club? Do you seriously believe that there is more demand for a new Famicom Detective Club than there is for a new F-Zero?
I put in the original post that Nintendo would need to pawn it off. If I had to take a guess at potential devs, would say either the Fast RMX team or SEGA returning. The only way the titles you listed got a second chance was due to this with the exception of Clubhouse 51, a very poor choice for the example as the DS game alone makes up nearly half of the total sales of all F-ZERO titles.
Should point out that these are heavily budget titles. The graphics on all are super cheap and content is fairly minimal. They wouldn't be able to get away with this level of production on an F-ZERO title quite literally for the reason you posted:
There is no such thing as a bad F-Zero game which is why I think Nintendo is so concerned about never making a new one again, they don't want to ruin the series' perfect track record.
The audience to production cost ratio isn't seen as worth it. Other series like Kid Icarus and Star Fox got hit with the same issue, they are too big to go cost-cutting, but are franchises that sell maybe around a modest 1 million these days.
You yourself said that F-Zero shits on every Mario Kart game, do you think more people today aren't aware of that? Nintendo actually needs a big racing game that shits all over Mario Kart now more than ever because Mario Kart World on Switch 2 is absolute garbage and a massive disappointment.
No, majority of Mario Kart's userbase does not.
They are different games entirely, with Mario Kart being a way bigger hit given how easily accessible it is by comparison. You are not going to move the casuals off Mario Kart and onto a high intensity racer with notorious difficulty. This is a big reason why Nintendo is apprehensive about the series as it is by no means casual friendly.
If anything were to actually compete with Mario Kart, and mind you with a giant asterisk here, it would be Sonic Racing. It is the only other racer that fits Mario's general style and with a large cast of recognizable characters while not being a budget title.