Typically the 'end' date on an effectivePeriod will get set once there's a known replacement date.  Prior to that, no end date is specified.  What that means is that if I grab an Questionnaire today that has no end date and then pause work for a year, it's entirely possible that the Questionnaire will have an expiry date by then.  But if I don't re-query for the Questionnaire, I won't notice.  Thus, if there's an expectation that systems must re-query for Questionnaires to ensure they have the current metadata (rather than caching them, which is an otherwise safe and efficient thing to do, given that we're filling out a frozen Questionnaire 'version'), then that needs to be set as an expectation for re-opening a work-in-progress.

Also, Questionnaire.effectivePeriod isn't marked as "mustSupport" in either of the profiles.  For this rule to work, we'd presumably need both effectivePeriod and effectivePeriod.high to be mustSupport.