I have no idea for sure, but I think KI intends to use everything that is shown on maps as Valencia isn't the only world with undiscovered territory. Mooshu also has a few unlabeled skyways and Corsair's Cove seems a bit empty. If they're going to add gameplay inside the machine, it would probably be in the next update since the current storyline trails off on finding a way to sneak back into Valencia. I don't know.
Quite some time ago, someone asked Blind Mew about what was in the Machine. His answer? 'Certain death, of course!' I thought this a satisfying answer, because of the implication of deadly perils that make for thrilling adventures. But are we ready for quite those perils yet?
Well... hopefully we'll find out! I tend to think though, based on the hints Blind Mew had been kind enough to give, that when we get to Valencia (a tricky prospect!) this will be a primarily an information-gathering mission -- and a keep-out-of-prison mission as well! Evading trouble in enemy territory is going to be a fascinating dance. Will we see more of beautiful Valencia and learn about its culture, peoples, and history? I certainly am looking forward to that. Will we find out more about Kane and his Elites? I expect so (and looking forward to that too!) Will we meet Kane? There's a prospect that can really (delightfully) terrify my characters, though you never know, we could be seeing him from within a crowd, and he never notices us...
I expect someday we will need to sabotage The Machine. But that may be a prospect too difficult to contemplate for us now... though you never know!