The Q school / Tour model is the way to go.
The current saturated average / minimum rounds / no demotion model is a flawed compromise, necessary to prevent bagging. The elite tier (or tour or whatever) wouldn't need those restrictions if it was so awesome that nobody in his right mind would ever bag out of it.
There are probably 30-50 players who win 90% of all the open tournaments, and perhaps another 100-150 who are capable of occasionally winning when at their best and with an assist from good fortune. I don't think these rough numbers will change all that much no matter how big WGT gets. The law of the bell curve keeps it that way. The names of those players will change as some of the big dogs leave and get replaced by others.
Therefore, the elite group should be small, and needs to have an out door. 100 with 50 in /50 out was suggested, but I think that's too small of a group with too much turnover...150-200 members with 20 in / 20 out seems better if it's done every month.
It might be best if the "out" group is determined by a rolling 3 month average. You wouldn't want to give dansamcam (for example) the boot just because he took a vacation.
So...back to the awesomeness mentioned earlier:
- Prizes. Real world goodies. Gift cards. 100 bucks at Amazon the first time you make the tour, and 250 bucks every time tour membership is maintained for 12 consecutive months.
- Pro shop: All gear available, and free. Yes, free. Do PGA Tour players buy their gear? Most of the players in this group are playing for free already. This is the trade-off for perhaps restricting some RG entry. (obviously with a ball-stockpile limit - can acquire a free sleeve only when owing 3 balls of that type or fewer? or perhaps all ball inventories show "unlimited" when in and revert to previous quantities when out?)
- Unique "I made it" pro shop accessories - custom (or at least exclusive) avatars. Balding spare-tire middle aged guy, perhaps?
- Fame, glory, attention, front page, golf channel, whatever. Groupies? Okay, too far...
Make it small, make it awesome...all of WGT is a better place. A thing to aspire to, and more opportunities for everybody. No new tees or green speeds needed.
Edit (add): I'm thinking the Elite Collection disappears from the pro shop since those items could be earned on the Tour. Big credit prizes for Tour events so the money-list grinders wouldn't need RGs. WGT, perhaps you track (or could determine) how many players play for free? perhaps this could be a guide to the size of the new tier.