Jumping to conclusions much? Sure, we had Walter, but I don't remember him hogging the spotlight in the two movies he had a major part in, yet after that, he just disappeared. I doubt Summer is going to be the same just because three characters aren't in it. If anything, I would like Summer to appear in grown-up Muppet form just so Disney can do more with her, unlike Walter and even Skeeter.
Plus, getting cancelled all of a sudden? Pfft! It's a preschool show! Those are guaranteed to have at least 2 seasons because it's such a lucrative market to the point of oversaturation.
Remaining cautiously optimistic here, the biggest worry to me about this reboot is that it tries to be like Dora, and judging by the brief clips shown, it doesn't seem to be the case. Would really like to see some Star Wars or Indiana Jones footage, too, so I'm hoping we see them come the show's premiere.