I'll likely buy and play it if friends come back. I have a few friends with whom I've played for most of the last decade. We all go away during expansions, but mostly come back for the first 2-3 months of a new expansion. Since we live all over the place it's a nice way to reconnect 'live' and fuck around a little with people I know and I don't mind spending that money for that play time.

Will I play every month for the 2 years after that? No. I used to do that... but I don't raid anymore and WoW isn't my solo jam.