I don't see a need for rotation, personally. Why rotate out perfectly acceptable and healthy upgrades and pilots (not to mention models)?
If 2.0 doesn't happen, the best scheme (logistical nitty-gritty aside, as I'm not knowledgeable about such things) would be:
(1) Quarterly FAQ/errata publication, consisting of (a) published changes, and (b) endorsement of the change or modification of the change two weeks later.
(2) Upgrades and pilots modified via errata.
(3) Interactions clarified via FAQ.
(4) Three-month open beta of new expansions following normal development and playtesting.