I'm hoping the tile system doesn't return, or that if it does, there's a higher chance of finding Feebas in the designated tiles + more tiles for it to be found in. However, I'd prefer an easier way of getting them, such as having an increased chance of finding them via Chain Fishing or through an outbreak. That being said, if the same system does return with no changes, I can just transfer a Feebas on over, no biggie.
Evolution-wise, I can see the Prism Scale being used to evolve it. I personally found maxing out its Beauty to be difficult in all games except Platinum (since you could buy pre-made Poffins), so I can't see them using that system again.