We haven't actually seen Tobi's Sharingan go in to MS mode. Secondly, his warping occurs in the hole in his mask doesn't necessarily mean it is linked to his sharingan. Third, if you link his warping ability to his de/rematerialisation then it could be that his abilities independent of his eyes that allow him such control.

As for those saying Tobi is Obito, why would Obito hate the Uchiha so much that he would be willing to exterminate the clan? Also, as someone pointed out earlier Obito was Kakashi's age and back then he would never have been able to fight Minato the way he did.

Thinking about it, the only person who Tobi could realistically be is Uchiha Izuna, Madara's brother. Only he would have pretty much all the knowledge Madara possesed, share the same hatred towards the Uchiha clan and harbour the same set of values as his brother. Add to this that both Madara and Izuna were competitive, it would make sense that right now Izuna is trying to revive the ten tails to achieve his political aims whilst Madara is going about doing things his way.

Ultimately the story of the Uchiha may come down to how two sets of brother interacted with each other, namely Itachi/Sasuke and Madara/Izuna. The latter seemed to hold their values above all other things and this led to the destruction of the Uchiha and wars in the Shinobi world, whereas if Sasuke can learn this and embrace the same aim as Itachi then this pair of brothers could be the ones who saved the Uchiha ultimately and ended the war started by the older set of brothers.

Throw in the mix Naruto and his new friend Kurama, Bee and Hachibi then you could potentially see the manga ending with Sasuke redeemed and Naruto being made Hokage as it is ultimately his power that swings the battle of the Uchihas.

This would require though the bit about Izuna dying in Tobi's story to Sasuke to be BS. Even if Madara took Izuna's eyes I'm sure either one or both of them would have been ruthless enough to pinch the eyes off another Uchiha and replace the ones Izuna lost.