Of existing franchises that I’d like to see more of:
Mystery Science Theater 3000 (I Understand Joel is trying to get this kickstarted
Connections by James Burke. The TLC incarnations weren’r as good as the PBS original, but they werre still worth it. And he’s written books like American Connections he could use as basis for another series.
Firefly, as noted
Asterix – the old cartoon versions were of mediocre quality, and I wasn’t thrilled by the live-action versions, but a couple of years ago they did a new cartoon version of Asterix and the Normans under the title Asterix and the Vikings that was beautifully done. AFAIK it didn’t get released in the states, even on video. They’ve done at least one other since, Asterix and the Gods, which I haven’t seen.
I could do without
The Prisoner – I loved the Patrick McGoohan 1960s series. The remake several years ago was terrible. I don’t think anyone else can do it justice.
Dragnet – Without Jack Webb? unthinkable.
There’s a whole other list of films I wish they’d remake, only the right way this time., but I think that’s outside the scope suggested by the OP.