Yep, that pretty much lists all the on-going concerns.

Some of the maximising delegators that are not otherwise involved in the sports tribe would be disincentivised, and would probably move their SP elsewhere.

This sounds like a good thing but could actually backfire, but like you, I'm not 100% on top of the economics (although you have a better idea than me). The SP vested into the tribe is of benefit in some regards I think, but the leakage from the promo account to delegates and then to market is certainly causing major selling pressure.

....some or the reward farming, self voting (particularly comment self voting) and shit-posting may subside a little. I don't think this is a major problem.

It has been reduced, particularly with regards to comments farming. However, the usual suspects have decided to just up the top level post count each day in order to maximize stake. This is where community moderation should come into play - is the post worth the sports, is the account being a selfish greedy sod, etc.

Users could nominate posts from newer members to curators for review. A simple set of guidelines could be used (like number of SPORTS posts, SPORTS token stake and so-on) and the best posts from newcomers pinned as featured posts. This would give new members that produce quality posts visibility, and a chance to grow.

I think this is a fine idea, and should be explored further. Cheers!