Sadly, I think the Unlimited classes are coming to an end.
The price to enter has gone through the roof as the parts become more rare and the speeds are getting too high to remain safe(ish) on the "long" course.
IMO, The Unlimited community has been a little tone deaf when it comes to "top speed vs safety" and I don't think the fans are showing up to watch a blood sport (heck, there are always the Bum Fights in Reno).