Well I've talked about the "Super-Bat" stuff and wanting to see Dick deal with more superhuman threats. This is just taking that to an extreme. So.....sure, screw it, why not? Nightwing as a spy was a pretty oddball idea at first too, so why not make Nightwing a space captain and see what happens? I mean, if nothing else it'd make an interesting change of pace for a while.
But a hard NO on the NTT cast. That makes it a Titans reunion, not a Nightwing solo. Bring Kori along, please. There's good history there and these two really need to reconnect (perhaps not romantically, but I'd at least like to see a genuine friendship). But Raven, Gar, and Vic? Definitely not. Especially Vic. I mean, you'd really have to work hard to make Vic anything *but* the star of this story; cosmic adventures is *too* fitting a role for a dude with a Mother Box for a heart.
Put Dick in a suit that has some Batman Beyond type abilities (I've mentioned it in the past and want this regardless of what direction anyone takes), team him up with Kori, and then use some D-list cosmic characters Dick doesn't have much history with. Adam Strange. Captain Comet. Space Cabbie (no, seriously, it could work).
Let Dick build relationships with a whole new corner of the DCU (the most well-connected man in DC becomes even more so!) and use characters who aren't going to steal his thunder.
As for a setting......The Citadel would work. Vega System might be too "Omega Men" but could still be viable. Reach-space would be too heavy on the Beetle stuff. Lady Styx's domain seems like a good choice. Or Dominator-space, though that feels a little....I dunno, predictable? Basic? But my personal favorite option is Almerac. It comes from the Super-mythos but no one has ever done anything with it. Their queen, Maxima, is a fascinating character and what little we know of their culture is interesting, but no Super-writer uses the Empire. So maybe Nightwing could fill in those corners of the map?