Only for future engine versions - you are able to continue developing and release your project with the one you already have under the previous version of the terms.
That is nice and all... but you still have to invest significant resources into building and training your team to use Unreal, and then if they change the terms for future versions, you are stuck on an old version if you don't accept those terms, until you retrain everyone.
Of course, open source projects regrettably become closed source projects sometimes too (see Hashicorps recent moves), locking you into the previous version of the project.... but, with Open Source, you can fork the project and continue- or ally with other members of the community to fork- often at a lower cost than re-training and re-tooling. An option that does not exist in the proprietary world.
The thing is though, there is no open source project even close to what Unreal Engine currently offers. It's just lightyears ahead in everything kinda? Editor tooling, asset pipelines, advanced rendering features, ... While you could build on open source tech and implement all the missing pieces yourself, that is just not going to be a sensible investment for most studios.
You'd be hard pressed to compete with Epic Games' investment in the engine for their own games and others, too. I don't think this situation is comparable with Hashicorp. Epic has more than a hundred engineers continuously improving the engine, doing research on new technologies like Nanite and similar, and all their improvements are available to you immediately. You have full source code available and are able to modify it as needed, you can also fork it under the current terms. As far as I know there were never any forks with significant traction, only to implement random features people needed in their game.
This is just a guess, but I truly don't believe we are going to see Epic Games turn evil like Unity has as long as Tim Sweeney holds more than 50% of the shares. Going public was Unity's death sentence - the tech no longer mattered, now it was all about extracting the maximum value possible before the company is run into the ground.
If every company that currently pays Unreal licensing fees instead donated half of those fees to Godot or O3DE, I think we would rapidly see the gap close.
That is obviously wishful thinking and probably not a good bet for a game dev company dependent on cutting edge Unreal features to make. However, not all game developers are in need of cutting edge, for many, Godot 4 will offer them what they need already. O3DE looks interesting, but seems only really currently usable by a company which plans to do a lot of custom engine work themselves already.
I am currently trying to learn Godot 4 in my spare time (which unfortunately I don't have enough of), and if I ever start to make money off it, I will be donating a percentage back to Godot development. I certainly don't begrudge a developer going with Unreal, but I encourage them to look at alternatives and what they really need to plan for the future and not be tied into the present situation.
My goal is to make some really good games in my 40s - a decade from now. So I might as well learn skills and build up on open source now. That fits that timescale.