Exactly. I think Tesla/Elon didn't originally expect to need to upgrade the hardware. With logistics and the cost of upgrading the vehicles, they probably aren't really going to make money on a lot of the already sold ones. Infact, I'm kind of expecting them to remove the option to add it in later, even after it comes out: with them telling people to trade in and buy a new vehicle if you really want it at that point, thats the way it works with every other manufacturer. I'm just hoping the lag time between them releasing it on new vehicles and the ability to schedule the upgrade on those who already paid for it isn't too long, but I fear it will be.
I think the option will only come back if the upgrades of the existing vehicles goes well, and the price will be based on that. I think they'll start shipping FSD in about a year, but not upgrading existing cars at that point. It will probably launch as highway driving only (on ramp to off ramp, including highway ramp to ramp interchanges, the navigate with autopilot with enough "confidence" to not pay as much attention/approve its lane changes/whatever)