My thoughts on a potential sequel:
I love the idea of GODZILLA: KING OF THE MONSTERS as the title.
I'd like to see something awakened from the melting permafrost (yeah, global warming message), or genetic tampering.
New monsters, pretty please. The Mutos were AWESOME, and a huge breath of fresh air IMO. Hedorah is the only Toho kaiju I'm interested in seeing (pollution is just as a relevant issue today), though the only classic kaiju I'd honestly be dissapointed with them choosing is Mothra. And, as much as I love 'em both, I don't think we need Anguirus or Rodan for this universe.
YES to Serizawa getting an eye patch. Call it fan service, but damn that's a good idea.
I'm totally satsified if we never see giant robots/cyborgs or mazer tanks... or space monsters (maybe King Ghidorah could be some horrible attempt to re-create Godzilla.)
I really hope this gets officially confirmed soon, boy are we in for another fun couple years of speculation.