Well, Little Mac has been subtly revived through cameo appearances.
After Super Punch Out! (completely different Little Mac), we got a cameo of the same guy in Fight Night Round 2. Then NES Little Mac appears in Captain Rainbow, Smooth Moves cameo, and finally Brawl assist trophy, before being revived.
I also think Little Mac lost his retro status. Especially not only because he just appeared in a retail game, but because they even talked about making a sequel already. So he's pretty much back in action, I say.
Now, I see where people are coming from when they compare him to Ice Climbers and ROB. But we could still say that Ice Climbers are retro characters (they haven't gotten a new game/remake as off late), and ROB is retro because... well, in my opinion he's retro because he's a NES accessory. They'll never make a ROB 2.0, so until that day, ROB is retro.