People rage quit in player matches that don't count for anything. You're never going to get around the rage quitting. All we can hope is that NRS has a way to punish those who rage quit.
I'd love to see a system like MvC3. If your disconnect percentage gets to a certain point, you can only play against other people with an equally high disconnect percentage. You're not allowed back in the normal populace until your disconnect percentage drops.
Beyond that, I don't care much about online ranking. It's never an accurate display of skill. I'd much rather NRS use a system in which the ranking is determined by the players. So basically, you enter a player match (there are no ranking matches) and you can rate the people playing on a scale of 1-10 or something. You can only rate each person once (to avoid boosting), but you can change your rating of that person once a month (in case they've gotten better... or worse).
You'd still get some minor boosting, and you'd have people giving out low ratings just because they lost, but it would still be a much better system than anything fighting games use these days. Plus, NRS already stated that you can make comments and rate players during matches, they would just need to tie it into the official ranking system.