I don't think it'll have that much of a legacy to be honest. It was one of the shortest generations yet, and the games weren't that memorable in my opinion. They weren't groundbreaking or iconic like Red & Blue, and they weren't improvements on previous games either. It's actually funny because the only thing I'll remember this generation for is introducing the Dream World, but you access that through a computer or other similar device, so it's not really in the games themselves. As for what other people will remember Generation 5 for, I'm honestly stumped. I can't imagine that people will remember the Pokemon because quite honestly, almost all of them looked reductive. I think people will remember the arguments about some of the Generation 5 Pokemon more than they'll remember the Pokemon themselves.