You certainly can't have franchises AND relegation - it's one or the other. I suppose you could do something like "If you're in the bottom 3, any of the top 3 semi-pro teams can pay you your franchise fee and take your spot." or something.
I don't think "major teams were partners with PSP", but I do think teams on the "PSP" side of the fence (at least their owners) seem more willing to invest gobs of money in tournaments. You wouldn't see JT or Evil or Zap or Kingman put the kind of money into tournament teams that Smart Parts/DYE/National seem to be willing to. And WDP paying a franchise would just be giving their money to themselves, so that's not helpful either.
The idea that you can take a team and eventually win your way into the Pro league is a romantic concept, but I don't think it's a realistic one. It takes years to do, and paintball players move around a lot quicker than that. So you don't really end up promoting and relegating teams of players, all you're really promoting/relegating is team owners. One team owner gets relegated, his better players get picked up by other Pro teams. Another team owner gets promoted, he picks up other pro players to improve his roster (or he risks just getting relegated again).
And if all you're really doing is promoting and relegating team owners, you might as well just sell the spots to a specific set of team owners and let them do what's already happening anyway, which is moving players up and down individually based on individual skill.
Who cares if the rosters are locked for the last two events of the season to 'make sure the same team wins the spot' when the entire team could change for the following season anyway?