The Broadhurst definitely seems the most likely given the timing, but they could be holding back on announcing depending on what else is coming up--maybe they're considering moving some things around. By November they'll have at least a few other open houses--the Longacre, the Belasco, the Lyceum, maybe the Cort or Schoenfeld, and the timing of Curious Incident's closing would line up perfectly for the Barrymore.
Regardless, I missed out on tickets off-Broadway, so I'm thrilled that it's transferring. And so soon!