Development Plans can change in time. How is this evaluation made? And by whom?

Maintaining a development plan is a Release Alert. It is a responsibility of the end-user to highlight this to the Escrow Agent, who in turn contacts the Vendor. If a Release Alert is not resolved satisfactorily, then this may be escalated to a Release Event. Release Alerts raise awareness that a condition may have occurred that could be a precursor to a Release Event.