I'll say again what I said earlier when this whole thing came up: To me when I think of Kermit the Frog I always think of Jim's Kermit. It took me a LONG time to warm up to Steve's Kermit and I think he does a great job. I didn't even go see Muppet Christmas Carol in the movie theater in it's original release because I wasn't ready for the "new" Kermit yet. But Steve does a wonderful job it's just not Jim. Artie isn't Jim though I think his voice is alot closer to Jim's than Steve's.
However, with that said, I think time, Artie could make a great Kermit but I wouldn't want to see that happen unless Steve is ready to retire or god forbid something physically happens to him. But I'd rather see a decent, passable Kermit which I think Artie's has potential for, than no Kermit at all. That was my biggest concern after Jim passed on: what was going to become of his characters? They've gone on this long and I think they will continue if the right people are taking over with consideration for what makes them tick as characters and not just does a good impression of the voice. That's why I think Eric Jacboson is BRILLIANT as Frank's characters particularly Grover because he's got the personality, movements, etc. that makes up what Grover is as well as a good voice. And I'm glad to have lots of new Grover stuff in recent years even though to me nobody will ever take the place of Frank.