With the lack of analog triggers on the JoyCon, I unfortunately don't see GCN games coming to VC. What I would be interested in seeing is financial information regarding the "slow trickle" method- does it really net them sizable enough profits?
VC has been around for a while, and people are going to want to transfer up digital purchases- seeing that digital transfers are the last bastion of backwards compatibility in the video game industry, Nintendo has to play it right in order to get people to even continue investing in the service. Here's what I recommend- if Nintendo continued their slow trickle bullshit and have their also bullshit "mandatory upgrade price" like with Wii U, their online subscription service should allow users to waive that fee if attempting to update a previously owned VC game. In theory, it sounds nice, but I don't know how they would stop people from just subscribing for one month and updating all their old purchases- but on the other hand, it's 99 cents an Upgrade on Wii U (and 2 bucks for N64, I think?) so if the service was around 15 dollars WHICH IT SHOULD BE, YOU GREEDY ASSHATS, people would essentially be waiving the price for around 7-15 VC games. If you factor in the idea that people will likely continue to re-up month after month to play online games, it sort of evens out.