Instead of $30 for 90 days, they should say $30 for 100 hours of gameplay that is accessible over next 6 months.
Yes, or a mix of those 2 ideas. 90 days or 100 hours of gameplay depending of the hours played.
If you don't play a lot everyday you'll get 90 days but the subscription will end if you reach 100 hours before the 90 days. Seems fair for both parties.