I'm solid through LK.
That said, if folks do want to take a month off in prep for LK that's fine. As it stands, once the Expansion comes out many of us will be hellbent for leather (or cloth, or mail or plate) to get to 80.
If it turns out that way, I suspect I would consider a 1-month vacation in advance of the expansion to let folks relax and gather themselves (since the only thing out of the ordinary for most of us that could be stressful before then would be Halloween). Those not interested in the vacation can certainly run Heroics with the rest of us.

Orin/Light/Fiad
P.S.: Those still interested in raiding over this period if we do go on vacation can take solace in the fact that with the next patch, all the current top-level raids will be nerfed as a result of the mechanics changes.