I can't wait for the return of private train cars. Imagine the casinos hitching up private cars to the Brightline, thereby improving their experience while subsidising everyone else.
Having branded luxury cars would be he fairly easy and could easily be a hit; private cars are unlikely to be feasible with your regular high speed electric multiple units.
[1]: https://www.trains.com/trn/news-reviews/news-wire/28-amtrak-...