At this point they need to do one of two things:
A) They need to make a balls to the wall heavy record. Crank it to 11, huge riffs, crazy unison solos, and a raw(er) production. No ballads, no chimes, no cheesy female narrated lyrics. Show the world that you actually have some balls left without Portnoy. This would also benefit Mangini because, at the end of the day he's a much better metal drummer than he is a progressive drummer. All the songs should be about 8-11 minutes long and melt your face off.
B) Try to make a truly progressive album. I know at this point in their careers it's hard to be innovative but bands like Haken, Riverside, hell even Steven Wilson are all doing more interesting things with their art. This might be blaspheme but they should get a producer who understands what DT is about (i.e. not Desmond Child) who could help reign them in and help them reach their artistic goals. There were small slivers of prog greatness in TA but it was covered in 2 hours of cheese, and a limp production. They need some help in the studio.