Well, yeah, they have a history of...let's say a "lack of urgency" when it comes to putting out new material. But this time around, fans shouldn't exactly be waiting around with baited breath. It's no secret that, while Russ hasn't quit the band, he has wanted to distance himself from it for awhile for a few different reasons. So we shouldn't really be expecting any particular timetable.
That said, I've been revisiting Underworld recently, and I still absolutely LOVE this album. I still easily consider it their best work ever. If/when we do get a follow-up, I hope it is in the same vein.