While it's true that the Wii will someday be replaced the VC could easily continue-on as it's essentially an online-store with some drm verification to authenticate files stored on SD (or future mediums). Any online-device could be setup as backward-compatible for VC with little effort. Also, expect somebody to hack the SD encryption or for it to be "leaked" should they stop supporting it.
As for pricing, if you don't want the game don't buy it. I think most price-complainers are collectors who MUST OWN EVERYTHING and are mad because they can't buy it all cause they're not rich enough waah waah wahh. Five bucks is nothing for a game. Stop complaining. I'm certain that as time goes on you'll see more creative ways of getting games cheap and/or free. Expect to see Nintendo sponsor contents and competitions with Wii Points as prizes. There are many tie-ins for Wii Points (nintendo currency) that will explain why this is setup as it is.
The original premise of this thread is right-on-the-nose. Nintendo agreed to let these companies take the early lead and this is part of how they got them on their system in the first place. Also, this lets 3rd parties experience the VC as a revenue-generating business rather than just a neat thing Nintendo is doing and making money off (from console sales). Ideally the trickle of back-catalog will last long enough to meet the inevitable NEW VC offerings. This will probably take an entire year but ultimately Nintendo wants Sega and others developing new games for the VC in addition to homebrew-level playres and small startups. If companies like Sega, Nintendo etc are creating new, quality titles for the VC this will make it a major major hit.
There are many tactics and strategies at play here and it's important to remember that the Wii has not been out for an entire month yet. Most people, myself included, can't even buy one yet. No chance. Nintendo is wise to use this time to work out kinks and get feedback so as to be fully prepared when the roll-out's second phase picks up steam and you start seeing LTTP and other popular games show up on VC along with more online services, more big games, Wii channels, etc. I suspect March 2007 will be Launch #2 for the Wii.
Lastly, don't forget the inevitable DS connectivity...