I think she already had plans on working with Dr. Luke again for KP4 but of course things have changed now because of the Kesha controversy and now the songwriting process has been delayed until she finds a new producer
I guess she could always sell the songs to other artists. That way we kind of get to hear it...
Walking on Air and Birthday should totally have swapped places. Both are bops but that way WOA would have got the single treatment but we'd still have gotten the godly Birthday vocals