Rather than requiring teams to get back to a hard limit of 85 for 2022 and beyond, that formula could be used until all covid year players have used up their eligibility.
At the beginning of each season the roster would have to be: 85, plus any players who would normally be out of eligibility but are opting to take their extra year.
If that or a similar model is not used, few if any players, beyond the one's exercising the option for the 2021 season, would actually be able to use that supposed extra year. Schools would have to severely limit incoming classes in order to make room for players with extra eligibility. Or worse, even more kids would be unfairly asked to leave various programs so that those scholarship slots would be made available.