I'm sure it will. At the very least it will have a special sticker on the cover. They've done that for basically every anniversary and 500 performances.
I emailed playbill.com requesting that they stock the RENT closing playbill in their store, and the man who wrote back said they were sure that they would be
that seems to ensure that some special playbill will be made. Maybe "goodbye, love"?
ALSO, if you are interested in buying this playbill, please consider sending an email to playbill.com so they know there is a lot of interest in it
This show has the type of fan base that will want a memento of the final performance so I am sure they will have a special playbill to accommodate them.
Didn't Les Miserables and Cats have special Closing Night playbills?
I think the Les Miz one had the words "Au Revoir" underneath the show's logo.
EDIT: MissAnneThrop, you beat me to it!
"You drank a charm to kill John Proctor's wife! You drank a charm to kill Goody Proctor!" - Betty Parris to Abigail Williams in Arthur Miller's The Crucible