3) Direct continuation with BSG:TOS ala the Richard Hatch vision. Might work, if only on a nostalgia basis, but could it be sustained? Can it it be done post-BSG2003 without looking dated and silly?
There's a (limited) market for a 'wrap up' of the original series, bringing it to a definite conclusion. I'd suggest a TV movie or miniseries.
I'd take the footage of Lorne Greene from Galactica '80 and construct it around that - with sparing use, CGI and stand-ins it could be done. The DS9 tribbles episode was fantastic, and that was years ago - it must have got cheaper by now !
If by any miracle it was a huge hit, they could try a spinoff. How about Apollo and Starbuck - The Twilight Years...