After listening to all of the podcasts, and hearing about how WDW is not doing so great financially right now, I can't say I'm terribly surprised that PtN will be going there for a while. I haven't seen it yet, but will in two weeks! I love MSEP, but based on the photos I've seen of PtN, I have a feeling it's going to blow my mind.
I don't know how it would be possible long term, but it would be pretty incredible to have both parades at DLR. But I suspect the rumors of PtN going to WDW permanently are tue, especially based on this announcement.