Speaking somewhat off the cuff, I think Savage crossed the line too many times; he's become more of a liability than an asset when it comes to advertisers and that's the kiss of death. These talkers run so close to that line so often that it doesn't take much to push them over it, and with ad revenues being what they are, just one mis-step can kill your career. Personally I loathe Savage so I'm not sorry to see him go, but I'm not terribly fond of this climate that encourages pushing the envelope so hard that we're in a one-and-done system.
Dr. Laura always struck me as being a one-trick-pony. She was effective...if one can call it that...when the mood called for a holier-than-thou figure on an anti-gay rant. But when the hate-talk-du'jour switched to racism and, more recently, to socialism/healthcare, she never really shifted with it. That was always Rush's greatest talent. I can't stand him or anything he stands for, but the man is quite the genius at reading/manipulating the national zeitgeist.
As for lack of progressive talkers, their absence is somewhat noticeable...but the queen of left wing, Amy Goodman, is on local cable TV about four times a day so it's kind of a different story there. Democracy Now! is really a TV show more than a radio show these days, anyways. Much to my annoyance, I might add...