McMillen was apparently approached by Cave Story developer Nicalis about the possibility of delivering a console port. The Isaac creator writes for Gamasutra that he was up for it, just so long as he could be kept out of the business dealings during development. And with that, The Binding of Isaac: Rebirth was born and pegged for a 16-bit visual overhaul. McMillen isn't sure which platforms it'll be released for yet, but there's apparently interest from Sony and Microsoft both.
You should really just go ahead and read McMillen's Isaac post-mortem at Gamasutra. Great stuff in there.