Frankly we can do with a bit less Witcher-esque games at this point...
...or at least games with what suits think makes The Witcher popular...
I have a lot of problems with The Witcher in the end, but one thing I will give it credit for; it proves the viability of a hybrid protagonist, in the same vein as Commander Shepard did.
I want that to be the case with Mass Effect, but I also want a bit more diversity in terms of powers and builds. How it was done in Mass Effect 3 was quite good, but it could be expanded a bit.
Like, imagine for a second an engineer track or tree that allows you to upgrade the Mako further. You can take that role or you can assign an engineer class to do it for you, much like how decryption and electronic skills worked in the original Mass Effect.
Does it serve a combat purpose? No, but it doesn't have to though. A bit more variety, mixed in with how Mass Effect did things in terms of character loadouts and power use in 3, would be the kind of perfection they need in terms of combat mechanics at least, and it would make the Pathfinder a more diverse character in the long run.
From Fallout 4, I think there is little they can actually borrow in the end, except the open world itself. How Fallout 4 set's mood and tone with the wasteland, with the environment and weather effects, is frankly brilliant. The first time I went into the Glowing Sea it was phenomenal....I want to see planets that are like that in some way.