Mike- I think you have identified a shortcoming. You may recall that when my son moved to Dallas, the first place I took him to look was your club. At that time, there were openings in the junior category and, with my urging, he would have applied but for the year-long renovation that was to commence shortly. He got in at one of your other peers and has settled in nicely. Perhaps a solution to the problem you describe is to expand a legacy category, perhaps with more playing privileges during non-peak times. Of course, much of this could become moot in the next 20 years as Boomers die off and are not back-filled by the Millies. And yes, hot retirement communities might face the same issues at the end of the Boomer cycle.
Re: Thorntree, that's a difficult market down there for golf. The old Oak Cliff CC nearby was renamed and went semi-private, then mostly public. Last I heard, a sale for residential redevelopment was considered, but ran into opposition. Los Rios CC in Plano went public and is now closed and slated to become open space. Oakridge CC in Garland closed, and later re-opened as a public (Duck Creek?). Lots of changes at this level of golf which will likely continue.