I don't have a problem pushing Callahan down to the third line. First of all, it would make the third line relevant. We have one of the least productive third lines in the NHL. It also wouldn't impact Callahan's game to a large degree. He will still get his ice time, even strength, power play, and short handed.
It will push Gaborik to his natural position. And in his natural position, he is vastly superior to Callahan in terms of production. You cannot compare a 40 goal / 75-80 point right winger to a 25 goal / 45-50 point right winger. Even with all of Callahan's intangibles. The top-6 is relied upon mostly for scoring. The defense becomes secondary for those lines.
Pushing Gaborik to RW on the 2nd line will give him an opportunity to return to 40 goal form. It will create a better shut down line on the 3rd line with Callahan on it. And it will create secondary scoring. Right now, if the top-6 doesn't score, the team doesn't score. Boyle scoring yesterday was a fluke. But how many goals have we gotten from Boyle, Powe, Halpern, Miller, etc.? That's exactly my point, putting Callahan there will only improve the situation.
And Gaborik won't produce playing with 3rd line talent. He's an elite sniper. For him to be effective he's got to be the one who gets fed the puck. Boyle or Miller won't do that.
Gaborik has looked great recently on the PP at the point dishing the puck and is a big reason why the PP has improved. His goals will come, just put him in his natural position.
Honestly, I think this team benefits all around if you move Callahan to the 3rd line. And that's no slight to Callahan. But if you could get Gaborik going at a 40 goal / 80 point clip, that will help the team more so than Callahan's intangibles on the 2nd line that he would still be able to bring to the table on the 3rd line and he'd still get his 20 goals / 40 points there.
As Michael Scott from The Office would say... "It's a win-win-win."