I watched the raw of the first of the two specials. It seems to take place early in the second season. No indication as of yet of the "I'm Home / Welcome Home" in the title being anything other than a reference to the fact that there haven't been any episodes produced for six years.
It looks like a fight with Feldrance will commence, though. I'm still holding out hope that Feldrance will end up dead somehow, contradicting his death in "End of a Dream". I don't think anything like that's been done before, but this is the first time I can think of that an anime was brought back from six years of absence (not counting remakes/new series). It can't just be about playing dressup, right?
A couple of other notes:
-Mahoro's limited lifespan is referenced, unlike in the Summer Special.
-For the first time ever, the nudity is obfuscated for the TV version. Not for censorship purposes, as it aired at the same time on the same channel as it did nearly a decade ago, but there's an increasing trend in ecchi shows to only show nudity in the DVD/BD versions. I suppose it's sort of like a nag screen saying "THIS IS A TRIAL VERSION." The sad thing is that I was certain it would be pseudocensored as soon as the new special was announced.