To me, "lengthy" is longer than 5 weeks but it's still a decent amount of time. And I'd definitely assume FOTLK would be open by then, but I don't believe they think that way anymore. If they want it closed for refurb it'd be closed regardless, IMO.
I think this attraction could use a good refurb. On my last trip in April 2013 a few things needed some cleaning, some effects in the seats weren't working and I'm sure the projector and screen could use a little clean up.