Warbirds is still in business and when I left 6 months ago the RPS was still in use. I was one of the many that didn't really like it. Early war planes are slow and that just adds to the time between action. Smaller maps for early war might help that, possiblg grow the available bases outward as the plane sets change. Regardless, AH has an arena for two sided wars and the possibility for rolling plane sets. Doesn't sound to be very popular. FSOs are also available. and custom arenas.
I would like to see more variety in my opponents but trying to force people to fly the matchup you want doesn't really work.