Pooh's Playground was meant to be "temporary,' but no one knows how long temporary is, in Disney terms..... As for anything coming to MK, there are a few plans...
1. Adventureland getting a new e-ticket (this has been discussed many times....)
2. Tomorrowland getting a new e-ticket, which would either go outside the tracks or in the footprint that includes CoP....
3. The area behind Pooh, Toontown, Grotto... Rumors were of a mountain, dark ride of mermaid, even Mermaid Lagoon from Disney Sea...
However, agreeing with YoHo, don't expect anything in MK for a while.....