This show is a way for Cumulus to grab more inventory. Framing it as the anti-Rush is garbage, eventually he will say something someone won't like.
Cumulus seems to have a strategy of maximizing profits by keeping as much of its content in-house as it can. They also recently announced that they will be doing their own traffic reports starting next month.
Huckabee isn't really the "anti-Rush," but more likely a kinder/gentler, and cheaper Rush-alternative.
Since Cumulus owns many of Rush's biggest affiliates, if nothing else, owning a good syndicated alternative will put Cumulus in a better bargaining position the next time Rush's contracts with those stations come around. And if, by then, Rush's position has been weakened because the election will be over, the big sponsors haven't come back, and the audience continues to drift away, then Rush will be looking for new affiliates in some very major markets, and at far less than "confiscatory rates."
And even if Clear Channel can find other stations to carry Rush, if those stations do as well as CC's own "Rush Radio" in Boston, then the fall from grace and fade to oblivion will accelerate, but Rush can still keep going as long as he wants to, or as long as his health holds out. Unfortunately, Rush appears to be lacking in "responsible self control" on the obesity front and that may ultimately have far more impact on the continuation of his radio situation than any challenge from the likes of Mike Huckabee.