Are you saying that an Obama disqualification would result in McCain as Pres. and Biden as the VP?
No, I don't see McCain becoming President under any scenario.
If Obama is ruled ineligible -- and that's a big "if" -- we would have one of the following: a) a set of Democratic electors voting on an alternate candidate; b) a Democratic Congress in charge of the Electoral Votes -- and capable of using either the 12th or 20th Amendment to string it out so that Biden becomes POTUS; or c) chaos.