Actually, I've seen American properties recreated as manga. When I was in
England last summer I came across a Japanese-produced X-Files manga
(untranslated, so I didn't buy it, although now I wish I had... does
anyone know where I could find it?). The characters looked, well,
Japanese, but they also looked like Scully and Mulder. It was very
interesting, and pretty cool. I've also seen X-Men and Spider-Man manga
that aren't just flopped versions of the American comics - they're
completely original productions. I've heard they're better than the
originals:-) So anyway, the point of this, is that the idea of Star Trek
as manga isn't too far-fetched, and it probably would have been a bit more
compelling with better continuity. Sorry if that offends Trek fans, but
while ST-TNG was pretty good about referencing previous events, I don't
think I ever saw any references to previous episodes in the original. How
much more gripping would it have been if Captain Kirk actually mourned the
loss of all those alien women with whom he fell in love? Just a thought.
It would be interesting if someone developed this into a fanfic! 
Jeremy