There’s possibly going to be some changes to the AI opponents, but nothing has been confirmed and they have been a bit vague about that part.
I don’t think there has been word on actually changing the custom maps.
Hotkeys are going to be more easily customizable in Reforged. Presumable a bit more like what they did with Starcraft 2.
And as for the main question:
Well, there most certainly is! Just take a look at my other thread: [Compilation] ALL we know so far!