Even if the GOP does take the Senate, there is little or nothing it can or could accomplish as long BHO is president. He will simply veto everything.
The important thing now is to put everything into place now and build the foundation for 2016. Just as the Dems did in 2006 and were well positioned for 2008.
If there are federal court vacancies in the last two years of Obama’s presidency, GOP control of the Senate could help prevent Obama from appointing radical liberal judges. Such nominees would not get confirmed by a GOP Senate, if the GOP stands opposed to such nominees, that is.