Tobi cannot be Obito. Jiraya trained Nagato, Yahiko and konan. After this Jiraya trained Minato and then Minato trained kakashi,rin and obito.
Tobi says he is one who gave Nagato the rennigan. Looking at the timeline; Obito would be a mere infant when Jiraya was training Nagato or he may not be even born at the time. If Obito comes out to be tobi it will be biggest blunder of the manga as long as there is some hax jutsu that allows time travel.. :D
Any way it is difficult to pull off something like Tobi = Obito if both statements are assumed to be true. And anyways there is no reason why Obito must hate kakashi and try to destroy the entire world.. that's just not kishi. I want to see Tobi's face and not sasu and Oro next chapter... please kishi don't troll us.