Simple question: What do you want the future of Classic WoW to be?
Start it all over again at Vanilla, then BC, then WOTLK, as everything is right now
Start over in Vanilla > BC > WOTLK with some major systems changes, all back of house though and not majorly affecting gameplay
Start over in Vanilla > BC > WOTLK with major rebalancing of specs similar to going from Vanilla to TBC and TBC to WOTLK. Maybe give Dwarves Shaman and Tauren Paladins in Vanilla.
Move on to Cataclysm, with no changes
Move to Cata with some adjustments (LFR, Talent System, Easier/Harder Heroics, etc)
Forever WOTLK
Personally, I think that it should start over with system changes. Classic Era and SoM get sent off to WOTLK servers. WOTLK Servers remain, but give people that don't want to play WOTLK forever the paid option to go to Retail at a slightly higher rate than a normal transfer. System changes could be updating the AH to retail standards, achievements, tweaking the LFG system a little bit, etc. Of course I'm not opposed to Dwarf Shaman and Tauren Paladins either.