Elmo and Count aren't going anywhere. Elmo especially. They recast him as fast as possible, and he's going to hold the same clout he always has. Nothing different at all. The Count... well, I'd tend to think his appearances might just jump up a little. Sometimes when a character is recast, they try and slowly integrate them back into the show, but it seems that they're more open to recasts now than when Jim and Richard passed on and Frank went from regular to guest.
So they would keep producing Elmo the Musical segments, but with (most likely) Ryan Dillon as Elmo? And if SS's curriculum continues to focus on self-control, could Herry Monster be brought back for some story lines? (recast suggestion: Matt Vogel)
Back then, SS still had a pretty solid and large group of people to perform the Muppets. I mean, Jerry and Frank spent
a lot of time on SS in the 1990s. That's not to say that they still don't have a dependable group. It's just a matter of Muppeteer availability now. They can't keep doing these Fairy-Tale one-shot deals. It gets stale after a while, in my opinion.
Jerry and Kevin are gone, Frank rarely comes in, and Caroll's almost 80 years old. Matt Vogel, Eric Jacobson, David Rudman, and especially Steve Whitmire aren't always around to perform Big Bird, the Count, Grover, Bert, Cookie, Ernie, etc. The only mainstays who have some years left are Fran, Marty, Carmen, and Leslie. (Bill Baretta, anyone?)