I love this topic, because it can be discussed in so many ways.
I don't think the band is overworked. But I do think the band members, themselves, probably are getting a little burnt. I expect them to take a pretty big break after the I&W 25th tour is done, at least from the public eye. I think once DT plays the big North American cities on the I&W tour, they'll have saturated the markets for DT for at least a few years.
I'm not saying DT is going on a three-year vacation, but I do think they will take a significant break to let things recharge and let their next steps, creatively, come to them. It'd be the wise thing to do. Their profile, in my opinion, took a little bit of a hit with The Astonishing. Unlike the last several releases, DT didn't seem to grow its fanbase much, and the record polarized the fans more than anything. JP and the band may love the Astonishing, but they aren't blind to that fact either.
I think The Astonishing novel, a potential TA/I&W live release, etc., will all be spaced out to keep DT in the music fan's face a bit, but the band itself will reign itself in for a few years before rolling out something new.