I would say many (not all) game engines could probably be converted, by finding common pattern in usage of inheritance and mapping it to rust patterns.

EDIT: Through automatizing this, or making C++ to rust bindings for it would be hard.

I mean creating inheritance graphs for entities is as far as I know already seen as an anti pattern since a while.

Things like ECM are nicely re-presentable in rust.

Many patterns of inheritance for code re-use tent to also not be too hard to represent in rust.

But I would argue that even if rust had inheritance engines like Unreal Engine would not be ported, at least not until they do a major rewrite anyway. Because of it being a lot of work with not too much intermediate gains.