Has the 18 core computer even been bought yet? What does a UE5 announcement mean to anything anyway? You had to know it was coming eventually, Epic always coordinates these with the console generations. They even specifically said it was timed for availability in 2021 to match the PS5 in the announcement.
Plus, there's nothing stopping you from continuing to use UE4. There's hundreds upon hundreds of things already in development for future release using it that will continue using it as their base. Epic's not going to drop support for it. Hell, they probably won't even port
Fortnite right away. Nobody else (except the very very largest partners) will even be able to start development on UE5 until 2021.
If anything this is manna from heaven, Wu can deliberately put off any kind of fake development until UE5 is fully available (i.e. not preview/early adopter) in 2022.
edit: This reminded me, I wanted to post something here for the people unfamiliar with it, Unreal Editor has these built-in game templates which are basically near fully fledged gameplay modules, you just have to produce the content and edit it to get an actual game prototype up and running:

The first person module is so complete that you can spend an afternoon and make an entire level with enemies and shit without needing to ever touch any code, especially if you go into the store for assets. There's tons of free stuff too like I could start that up and instantly place a hundred different kinds of trees and bushes all over the default map because they're free in the store. Even physics are built in, you can change the gravity through a simple box and whether or not physics effect objects with a checkbox, there's all kinds of lighting you just drag and drop, etc.
That's how easy they've made it. So when you see a Wu or Jake Alley whining about how obtuse it is, they are literally just being lazy, you don't even have to code anymore in UnrealScript because it's fucking gone, it's all menus and boxes. In theory, a faggot like Wu could easily take two months and create a working prototype for Revolution 62 or whatever with placeholder art and assets they could then shill on kickstarter, etc. UE3, which Rev60 used, required like at least ten times the work probably. And IIRC, it wasn't entirely free like 4 and 5.