Maybe not. It seems that some Senate sources are saying that they consider the Constitutional provision that a Senate term is six years, no more, no less, to be controlling, which would have the appointee, Dean Barkley, serve until January.
This means that it'll likely wind up in the Supreme Court, since the issue may well decide control of the Senate during the lame duck session scheduled to start 11 November. If Talent takes the Missouri seat, he's seated immediately, and thus control of the Senate is in Barkley's hands. He could hand control to either party. Obviously, the parties can't allow that.