Some ramblings here....
To address the Evil Doctor's question... I probably wouldn't notice if development of T5 were officially halted. At this point I have enough crunchy Traveller goodness on hand to hold me for quite a while, and if nothing is forthcoming from Mr. Miller - well then there are other licensee's working on things.
I *would* like to see a lot more separation between the rules system(s) and the background. It really irked me how much editing and expurgation had to be done to the MT

layers Book to get it to the point where I could hand a copy to my players for an 1105 campaign without dumping spoilers. Such a thing would be impossible with TNE as the rules and setting are more tightly intertwined than Win98 and IE.
But of course I fly in the face of conventional wisdom (probably economics too) by insisting that a great RPG does NOT have to come with a full blown setting woven into its chromosomes.
I really love the rules system embodied by CT and MT (i.e. CT++) - elegant and adaptable to many different eras and settings. MY preference.
Likewise, I have a lot of respect for the work and talent that went into the GDW 'house' system, Gurps and D20 - they just don't happen to be equally to my tastes as a ref (GM).
I'm also a big fan of the OTU - mostly the Spinward Marches around 1105. I like the idea of two parallel histories starting in 1116 and would like to see more development of the 'Strephon lives' timeline. The forthcoming IW sourcebook from SJG sounds fascinating, and I am also waiting to see what MJD does with the 1248 sourcebook. Hopefully it will be a great example of a rules independent OTU sourcebook, do incredibly well and spawn a wealth of system neutral OTU books in *all* eras.
The system neutral OTU sourcebook is a wonderful thing... everyone who plays any version of Traveller can use one and they would serve to keep the Traveller flame burning in the most efficient way possible.
That said, I'm firmly in the camp that would like to see a setting neutral, minimal errata, CT++ released, which could stand as the definitive 'Traveller' rules set. It was very good and minimally broke - *just* fix it. (yes I know, I'm an old fart - sue me)
I wonder what a license to do such a thing would cost..... Oh well, since I don't have a large fortune to turn into a small fortune in the game biz, the question is moot.
It seems that Marc is not headed in that (CT++) direction either. Well - he's the game designer and if T4++ is what he wants then that's his prerogative. I'll check out what (if anything) he releases and try to judge it on its own merits. In the meantime I'll be among those clamoring for more reprints and errata free MT .pdf series.
Anyways - just my cr0.02 heaped onto the debate. Enjoy - discuss.
--michael