I think it remains to be seen. Unity's big upcoming feature seems to what they call the Data Oriented Technology Stack. Essentially, this supposedly allows you to put far more non-static objects onto the screen than is usually available in a game engine. I do agree though that what Epic's doing here is a huge deal.
That's the big question, isn't it? Obviously every mobile game is going to benefit from it, because it will save battery life. The greatest question related to this for me is how many games that couldn't be easily made before are now doable? I imagine that Total War style games will be much easier to make with Unity.
