I wish Disney would put the entire original show's soundtrack on Spotify (as well as every other ride audio file) but I'm sure it has something to do with the copyright of the artists and the songs. Really too bad.
As for Frontierland's fate, I think converting the land into "Dixieland" would be an easy solution that allows for the incorporation of Tiana's, Country Bears, and the Rivers of America. Big Thunder, then, can be part of a new take on Frontierland beyond the railroad, one that includes Western River Expedition.