The official line with respect to the AOPVs is that there will me a 'mix' of regular force and reserve crew members and as far as this goes I believe it to be accurate.
The simple reality is that the navy as a whole is short a great of sailors. Estimates in the main stream media have quoted various officers as estimating the shortfall of around 600 or so on each coast. The MCDVs themselves are short significant numbers and as a result the navy (again as a whole) is unable to man the 10 MCDVs it would like to man on a continuous basis (the other 2 are usually down for an extended refit/maintenance period ona rotational basis).
To understand what is probably meant by the 'mixed' crew concept you must first understand that there are really two naval reserves in Canada. The first, comprising between 1500 and 2000 out of 4,000 or so naval reservists are those members of this formation who are employed on a continuing full-time basis with the forces. Most are employed on either coast in Ottawa or in Quebec City (NAVRESHQ, CFFSQ etc). By and large these personnel are on 6 month to three year contracts for a given position (not unlike a regular force posting). These individuals have no civilian careers, are not registered in a University and are unlikely to pursue either. They do not belong to a NRD unless they have been 'posted' there on a full-time contract. The vernacular for these individuals is 'permashads'.
The other half of the NR are the traditional reservists with civilian jobs, etc etc.
The simple fact is with the current manning levels with the navy as a whole the senior leadership within CMS has no choice to include reservists in their manning plans. I would suggest that this applies to FFHs and DDHS as well as MCDVs, AORs and ultimately AOPVs. What will change however is that the AOPVs will not be 'primarily' manned by reserves. They will simply be manned by whomever is available from the fleet. The implications are that the senior positions (CO, XO, Cox'n , CERA etc) in these ship will not necessarily be reservists, even those that are nominally 'reservists' or permashads.
My expectation is that a significant amount of the crew would be regular force given the nature and types of personnel required to man them (so far as this is really known at this point). The engineers on the MCDVs are, at a formal level at least, considered merely operators. [I know that they actually do much more than that, but the training system considers them as mere operators and not maintainers or repairers]. To transition all these 'reserve engineers' to the AOPV will require considerably more training (particularly in diesel repair and theory) as the vessels will be operating well away from a support base. Similarly reserve MARS officers (except perhaps very junior ones) may find themselves 'squeezed out' of this platform as they lack the formal training for vessels which will not be considered 'minor war vessels'. Other trades including NESOPs, Hull techs etc which may be required are not trained in the NR.
This will require a substantial change in focus by NAVRESHQ and the reserve formation if at the time the AOPVs are introduced the MCDVs are decommissioned as we will 'loose' the MCDV manning as the primary focus of the formation and revert to our general manning mission as has been the historic mission of the formation.
As far as the future usage of the MCDVs my general sense is that they will in fact be decommissioned (in their entirety) for two inescapable reasons. First they will be at that time (5-8 years from now) near the end of their expected life cycle. The midlife refit was cancelled. Operating and maintenance costs associated with these platforms can therefore generally expected to increase at a higher level than has been the past. Second as explained above the fleet simply does not have the bodies required, especially full-time bodies, to man the MCDVs and AOPVs simultaneously along with all the other platforms. So unless there is a reduction in other platforms (AORS, DDHs) we simply won't have the bodies needed.
As far as the idea of using them in the FP role. My response would be to look at what happens now in these type of exercises. And then ask is there anything an MCDV can do that an AOPV or other hull (Orcas?) can't do better.