You have to think that the Hollows will be back, and in a big way too... The end of the new intro certainly suggests that the Hollows will be coming back into play in grand fashion soon.

I mean, it's the opportunity they've been waiting for isn't it? Soul Society is in turmoil, fighting crazilly amongst themselves, preoccupied with Rukia's execution and the interferance of the ryoka (Ichigo and crew) who are posing a greater problem than they've ever seen from the outside. If you're one of the Hollow elite, you've been itching for a chance like this one... I can't imagine them just staying idle... Maybe they'll even make it to Soul Society in the confusion (holy shit that would insane, a total war)