@Nikotem
Totem should consider charging an additional fee for upgraded cards. This would give you additional revenue and encourage you to continue with the remastering. I suggest that the fee be 5 credits. If I buy a 1080p card now, I'll pay 20 credits (less my discount). If you upgrade it and I want the upgrade, I pay an additional 5 credits (less my discount). If I wait till after the upgrade I pay 30 credits (less my discount = 3 credits). I think this is a positive motivator all around. First it encourages me to buy 1080p cards that are eligible for a remastering. Second, it encourages you to do more remastering.
This same pricing could be applied to remastering 720p cards to 1080p. I have more than 600 720p cards and about half could be remastered based on their card number. (I understand that cards higher than about 700 were shot with a 1080p camera.) Many of these cards are from models I really like and I'd be delighted to pay 3 credits per card to be able to play them at 1080p. Right now, I seldom play 720p cards because they look so bad on my 4K display, but 1080p cards are OK.
Please consider this. You could make some additional money and I can play some favorite models more often.
I realize this is likely to require some significant changes to your software and database. I'm a programmer and a software designer. The changes are not trivial, but it can be done. The trick would be to add a maximum_purchased_resolution to the database table that stores each members card collection. Then you'd need logic to check this. The UI would need to change to warn the user that the upgrade for a remastered card has an additional cost. Again, this is not trivial, but it can be done. I suspect the additional revenue can more than justify the software development costs.