initially the plan was like this...
obito collects all bijuu.....revives madara....madara becomes juubi's jinchuriki....projects his eye on the moon...performs mugen tsukiyomi......right!!
BUt alas nagato died....bijuu collection not finished....so.......
obito might hv concluded that ....I HAVE TO GO FOR IT ALONE.......
I think ...he wasn't sure that whether he could be able to become juubi's jinchuriki or not....so he LEARNED EDO TENSAI FRM KABUTO...(i dont think a calculative person as obito...will do a a thing i.e of no use...)....IMO he kept THIS as PLAN B...in case he fails to become the jinchuriki.....he will go find the body of rin and would edo her....and live happily
OR......(most preferably....as obito not only wanted rin...but also a world that contains...him,kakashi,rin...a world where heroes will not have to make pathetic excuses in front of graves....so on...)
he learned edo tensai...so that he would say the seals to edo madara ....and by doing so he would make him(madara) free....
may be i dunno....
