Big E can probably be big for WWE. From what I've heard of him, he moves good for a man his size and is a good wrestler. Will he replace Henry? In time, I think he will, but Henry isn't getting fired for it. When Henry retires, he'll likely be a backstage guy
I saw an interview with Henry sayng he may not come back, he's thinking retirement but it would on his own terms when he wants, this Langston kid has future but that doesn't mean he is Henry replacement
Mark Henry had his World Heavyweight title run, he can retire without regrets now. I only wish D-Lo had done the same. It's interesting how a career mid carder like D-Lo, championship wise, had one of the better runs in WWE history (championship wise).