Gang,
Ya know, I went to Cass a few years back. Loved it. AMAZED to find it was operated by the park service (I think I'm correct). It wouldn't bother me at all if both states, or the FEDs, or all three entities operated the CATS as a coop park service.
I suppose there is a long tradition of opposing this kind of "take over" within the powers that be at CATS, but it doesn't seem like such a bad idea if the road could be operated in pretty much the same way and great stability could be achieved by institutionalizing it. I'm thinking along the lines of a fully functional National Historic site rather than purely a park. Shooting from the hip here.
Besides, I think the entire area would make a nice park. And it might be a good economic incentive for the entire region, eh?
Otherwise, best bet might be to put a full course press on a Bill Gates type who just loves steam locos, and get a trust fund established and inked in on his will. Gary