Well, although this is quite vague, a way to beat obito must be found. For starters, Kakashi could probably send a Naruto clone to the other dimension, and he could just spam attacks until Obito was drained of Chakra or killed.
Then, the only real problem would be Madara's control over the Juubi. If the Shinobi alliance could find a way to slow it down for a little while, Kakashi could (in theory) send Madara's whole body to the other dimension. This way it would not regenerate in the regular dimension, because the body would be whole, just in another place.
Because Obito would be dead, no one but Kakashi would be able to bring Madara back (which I doubt he would).
The only problem is Kakashi wouldn't be able to travel to the other dimension without being obliterated, but he went without doing that before, so not doing it now shouldn't be a problem.
so, what do you all think?