I think the "retro-Trek" thing has been tried, and failed with "Enterprise" already - Any future Trek that does get made should be set post "TNG/DS9/Voyager" in my less than humble opinion. Anyway, the story of the Enterprise C already has been told, with actors who'd be too old (and too unknown to be featured in a big Hollywood movie) by now to reprise their "Yesterday's Enterprise" roles. Plus, any investigation of the ST timeline reveals that the "C" had a very short career anyway that would be unworthy of too much retelling in the greater scheme of things..... The Enterprise "B" would be more worthy of its own show (as long as George Takei would be up for it, and you could put up with having to cope with another series full of blinking Tuvok......) Plus, the "Ambassador" class is a really cr*ppy and ugly ship design that couldn't carry a film or series on its own (although not as preposteros a design as the ludicrous, 200-years-earlier-"Akira"-ripoff, much-more-advanced-looking-than-the hundred-years-later-NCC-1701, Enterprise NX-01)...... Overall, I'd say no....
And yes - I am an absolute ST spod on the quiet, and (sort of) proud of it!! !! (ish)
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"Heeeeeeeeeeeeere's Johnny!"