Well, for me it is one of the worst in the DT catalogue, so no way it can be considered one of the greatest of all time..
But, leaving aside each one's personal taste, I think to answer your question one should ask wether this album is going to "change the course of music history" (= greatest).
And I think the answer to this question is a clear NO: no matter how much you like the songs or the production, or how amazing is the delivery by each band member, there are no musical breakthroughs in here, and it's certainly not going to create a new stream of progressive metal music, it is not going to push legions of teenagers to embrace an instrument, or anything like that.
The only DT album that can compete in this category is Images and Words: you might not love it as much as this one, but it certainly created (or at least reinvented and made popular) a musical genre (the progressive metal), even though a niche one.
PS - of course all of the above is just my opinion, it's not an universal truth, but I think it's going to be EXTREMELY unlike that this album is going to be more influential of I&W.