Logically there has to be an available option to upgrade to the new FSD computer, if a subscription to FSD is made available, as you cannot use FSD on a 2.5 computer. Purchasing outright the 10k FSD upgrade gets you the computer, which is an option for some/most/all of the Model 3 owners like myself.
And for the record, it still is being pointed out incorrectly that "all Model 3 after April 2019 have HW3..." which isn't the case. I have June 2019 with HW2.5 and there are those who have reported delivery after June 2019 with HW2.5... its just that the supply diminished after that. I don't blame Tesla for this, but there's no automagic assumption of HW version in your Teslas -- just understand that if you purchase FSD, you are entitled to the upgrade no matter what version, as well as the software capability.