The bottom line is that the only way for things to be fair is for the percentage of reservations for each week to reflect the percentage of points versus week ownership; thus, for example, if a resort has 3 days for check-ins, and, for argument's sake, 240 villas, and if 50% convert to points, then 40 villas each day should be reserved for point reservations, regardless of whether that is for points owners using home resort priority or exchanging in, and 40 villas each day should be reserved for weeks owners booking in their own season according to the rules currently in effect.
I try to avoid using the word 'fair' for any type of reservation system change that developers implement unilaterally and undemocratically and inconsistently which divides an existing owner base, since I consider such action to be inherently 'unfair'...
The bottom line is that those 240 villas will all be given implicit point values, whether owners convert or not. When a weeks owner makes a reservation, they are in essence spending their weeks point values in full. Only fixed owners are guaranteed the granularity of a specific week during their reservation window. Seasonal owners are guaranteed a fight for the best weeks out of the seasonal pool. To the extent that one owner is helped or hindered in that 12 month (13 month ), first come - first serve seasonal reservation system fight as a result of their accepting or declining membership to the new points program.... well, I would consider that to be 'unfair' when it is allowed to happen without a majority vote.
I would be upset if I called out 12 months in advance and could not secure a seasonal reservation that was still available to the other pool of seasonal owners, be it points or weeks. And, I would be extra upset if Marriott cut into that fight and secured a disproportionate share of units on behalf of one type system (points or weeks) over another. I'm unable to see 'fair' in this change. Time will tell how this all plays out.