That should be its name right now.
Pecos Bill and Splash are two differing Disney IPs. Under the rumored change, they'll be one Disney IP.
And Country Bears will fit because they aren't "the Frontier." They are "The South" (singing Southern songs from the 1950s).
Frontierland has regularly mixed up "the Frontier" with "the South." At the time of "the Western Frontier," the South was no longer "Frontier"... it was settled.
And across from the two Tiana New Orleans attractions is a Mississippi Riverboat. And a Mississippi Valley hang-out of Tom Sawyer.
And Diamond Horseshoe is akin to a Missouri saloon. And St. Louis was settled by the 1830s. Not much of a frontier land during the time of Mississippi steam boats.
The whole area could be called Ol' Mississippi Valley. BTMR is the one standout. It can be it's own mini-land... the new Frontierland.