Highly unlikely. I can’t see any reason a game engine would want to use one of the worst parts of C++ when it already has specialised libraries of it’s own that are much more fit-for-purpose. There’s nothing stopping you from using STL right now, but you won’t find many others doing it and for good reason.
Possibly, as that is where the engine was heading anyway. Most of the newer engine features are sectioned off into their own modules. Naturally, there will always be dependencies.
Nonsense. The garbage collection and reflection system is one of the most powerful parts of UE4, and again, it’s properly fit for purpose. There’s zero reason to suspect any of that will be removed, or that much of the underlying engine architecture has changed at all.
The answer to this thread at large is the same as it’s always been - UE’s own containers are fit-for-purpose and in most cases far superior to the STL/STD counterparts.