That is a pretty intriguing question. I think emulation will be retro for different generations of life. Maybe in 20 years all the millennium babies will be remembering their mass effect, halos, assassins creed etc.
Then i think you'll have that small niche who were interested in where games started or where they went from early incarnations.
I never had an amiga in my life. With emulation possible i want to try every system no matter how horrible or how bad. Hell i am in the Amiga EAB/Lemon competition and enjoying myself.
I love all walks of consoles. I feel the older computers/consoles brought more sense of what a game should be and not how life-like can we make this game. And the games were hard as hell (usually).
Retro gaming will be an underground cult that never really fades. Much like shmups have continued to persist through time.