So in this latest chapter it's pretty much been confirmed he's not Obito, because Madara has likely already met/known this person.
When I first heard about that theory I always thought it was dumb. It made no sense outside of the eye thing. Obito was jut some random kid who Kakashi saw die. He had no reason to be innately special. He had no individual interested in reviving or protecting him. There's no reason for him to be anything other than a dead mook inserted for the purposes of Kakashi's backstory.
It wasn't totally stupid. You only suggest it because we have reason to think he's dead. But let's be real, here. In the Naruto universe, someone you saw die still being alive is far from the weirdest thing that plot-no-jutsu has created.
Not to mention that we already saw, by the point you found out Tobi had a sharingan, resurrected corpses working for Pein.
Obito would have had one sharingan, and Tobi's mask only had one eye slot, suggesting he had only one eye. They looked similar enough (in the context of the Naruto universe) as well (largely because Tobi had the traits Uchihas had, which makes sense since he is an Uchiha).
Once it was established that he was Madara, there was really no reason to believe the theory. But it was far from absurd before that.