We discussed this at the April 2015 EC meeting. From the minutes:
Mike Milinkovich reported that Eclipse has a similar process and that they use the term "archiving". Archived projects are no longer current or supported. Patrick asked whether the TCK for an archived JSR should be supplied. Mike suggested yes, noting that no legal agreement lasts forever.
There was general agreement that we should define some kind of archiving process. Just as the PMO regularly reviews potentially dormant JSRs they should also perform regular reviews to ask Spec Leads whether their JSRs should be archived. Any actual change of state should only be performed after several months' public notice.
John Weir asked whether an archived JSR could come back to life. Mike responded that it should always be possible to re-start an archived JSR.
We agreed to keep this topic open and to discuss it further in the Working Group.