Now this is a very touchy subject for me.
Back in 2010, I was a CP and worked at Pecos Bill's. Frontierland has always been my home away from home, and I never thought it would ever change this drastically. However, I really think this mock up is a really wonderful solution for the potential theming issues in Magic Kingdom. I don't know if Disney would be willing to go as far as retheming the whole area like that, but I think that would really sell the introduction of Princess and the Frog. If they're going to force inject an IP into a ride as iconic as Splash Mountain, they should be willing to go the distance and commit to representing the IP. It is CRAZY to me that Tiana doesn't have a restaurant in any park yet. It's literally the most logical decision when it comes to theIP, and retheming a restaurant really wouldn't cost all that much in the great scheme of things. Sure, losing Pecos would really be hard on my heart, but if it meant Tiana finally got her Place, it would be worth it. Granted, Princess and the Frog came out one month before my first shift at Disney World, so I'm heavily biased.
The only thing they'd have to really consider is the costuming. As it stands, Pecos Bill's costumes are very uniquely designed because they're one of the only costumes in all of Walt Disney World that are designed to fit into two lands. The Cast Members who work at Pecos are the same that work at Tortuga Tavern as well, so the costume is uniquely designed so it would blend into both Frontierland and Adventureland. We were some of the few Cast Members who were allowed to walk back and forth. An easy fix would be just re-costuming the Tiana side, and having a set cast for Tortuga.
All in all, I really hope this is on Disney's radar in some capacity. It doesn't all have to happen at once, but I think it would be really special if this came together one day.