I want to love this idea, but I just can see it falling into the same preschool movie ghetto the last 2 Sesame Street films fell into. Let's face it. FTB, great movie as it is, didn't make that much. Less than most Muppet films, to be precise. It's only after it hit home video and TV reruns that it became a cult classic. EIG basically hit when the DVD's hit the 5 dollar bin. Even then, it's because it was a cheap DVD with Elmo on it to shut kids up for 80 minutes.
Now, I would absolutely love to see a bigger budget Sesame Street theatrical movie. I'm sure everyone here would. I just don't see it being successful enough to pull parents into theaters for 80-90 minutes for something they can see for free that's still on television and in production to this day. Though, Spongebob's popularity made his second film a modest success, so I could hopefully be wrong.