Even you don't believe that Carson will only carry one state.If Carson get's the nomination the Republican loss will be on the scale of Mondale '84 and it will be fun to watch
That very candidate would carry pretty much the entire Southern USA not called Florida.
Would he still lose? Most likely.
Then again, you might want to remember that as one-sided as that was, the Democrats actually GAINED two Senate seats that year. They lost 17 House seats, meaning a repeat performance will give us 56 Republican Senators and a House GOP majority.
If you think the party hierarchy wouldn't take that result in a second, you're mistaken. It all but guarantees a filibuster-proof majority in 2018. Sure, the country as a whole loses (like always), but the GOP certainly wouldn't mind Carson losing and gaining in the Senate and holding the house since he's not 'really' one of them anyway.