IMO it's absolutely essential that one of the eras/milieux presented in T^5 be the post-New Era Future, circa 1350 or so -- enough time that Virus and the Empress Wave and whatnot will have been able to run their course as plot elements, but still close enough that we'll be able to recognize the antecedents.
Exploring 'future history' is a nice option/gimmick, and fine for a licensee like T^20, but "real" Traveller should be about open possibilities and looking forward, not back.
Furthermore, although I'm not especially crazy about most (any?) of the changes TNE made to the shape of the OTU (Virus, Empress Wave, RCES/Hiver puppets, psi-friendly 'democratic' Regency, etc.) that's what we've been given and we must deal with it as best we can; serving up some 'return to status quo' 4th Imperium won't wash -- that's what GT's 'dreamworld' is for -- T^5 needs to explore the frontiers of the Great Unknown.
In addition to that, other milieux/settings I'd like to see:
Interstellar Wars
Psionic Supressions
Zhodani Core Expeditions
Solomani Rimward Explorations
Maybe it's just the bad taste left by the T4 fiasco, but I think Milieu 0 was a turkey, and I'm not in the least enthusiastic about M:200 either; especially not as the default/primary setting. Save the past for supplements; give me the Future!