I wish they'd return to the spirit (not style) of albums like Awake, SFAM and SDOIT, where they where trying to push their ideas as far as they could take them. On the first disk of SDOIT they where "experimenting" with different kinds of underlying atmospheres they could fit into their traditional band setup and gave each song room to breath. Awake was dark and very musically fluid, they where drawing from many places but the where consistent and effective in how it manifested, it was also a really dark and personal record. SFAM was an exercise in building 75 minutes of music around a bunch of simple themes and melodies, which led them to quite unusual and dissonant riffs (as hinted in Metropolis pt 1), I wish they would mix it up more like on that record; you got simple chordal writing, higher register riffs, highly chromatic instrumental sections, a larger sense of structure in which instrumental sections form an extension of previously referenced motifs, a constant sense of pacing (continually developing story) and a playfulness of styles (as seen in beyond this life and TDOE).
DT COULD do it again but I don't feel as though they're in the mindset to take a step back and think about things from a broader perspective again.