Personally, I think that the NES side of the service is a bust because they're not really offering anything new, even though they really can't at this point. Most of the console's best games will never see the light of day, on VC or whatever other service Nintendo offers:
-Bionic Commando. Capcom wanted to do it, but Nintendo outright refused to let them.
-Contra: for whatever reason, the most widely-beloved entry in the entire series has never been released on any service (the arcade game was released, but I never thought that it was as good).
-The Capcom licensed games: Little Nemo, Chip and Dale's 1-2, Ducktales 1-2, Talespin, Darkwing Duck, Willow, etc.
-Tmnt 1-3. The first game WAS released on the Wii VC, for a limited time and at somewhat of a premium price. The license has shifted hands since then.
-The MacAdventure series (Shadowgate, Deja Vu, Uninvited): now, these games COULD be released, seeing as how Shadowgate was released for 3DS in Japan. I doubt that it will happen, though.
-Games made by companies that either no longer exist, or have left the industry. Vic Tokai--who did Clash at Demonhead, Golgo 13--for example.
I really don't think that there is a way for them to make the NES exciting again. Between the Wii/Wii U/3DS VC and the NES Classic, they've sort of overplayed their hand. There isn't much left that they could realistically release that hasn't been released a million times over. I'll still beg for a rerelease of Nightshade, though.