If legacy servers came about, I'd try out Legions as well, assuming they would be bundled as one account package. It's not likely to hold as much long term commitment as Legacy, if any, though. Interest in Legacy and Retail aren't mutually exclusive, as you seem to wrongfully & illogically assert?
If Legacy doesn't happen, then I'm not wasting more money on Blizzard / WoW. WoW is lower quality. Starcraft - hmm .. Warcraft RTS is AWOL, Diablo is lower quality. Not the same company any more that I grew up with. There are hundreds, if not thousands of good games by other companies to play for now.