Yes. And I expect that Tesla will release FSDb to all FSD cars to make good on their stating that City Streets FSD was 'Coming Soon'. This does satisfy their obligation for 2019+ FSD cars. I expect them to continue to release updates until they exhaust the improvements they can make with HW3. But I very much doubt they will provide free HW4 upgrades to those cars. Installing new cameras and AP computer, even if there is no new radar or significant wiring mods, would be cost prohibitive in parts, labor and warranty costs for hundreds of thousands of cars.
I don't think you're right on the costs if there's no wiring or mounting mods needed.
You'd be talking WELL under 1k total cost in parts and maybe 2-3 hours labor, for making customers who paid a minimum of $6000, and many 10-15k, happy.
They've already done it once for the HW2.x buyers-both computers for 2.5 owners and cameras for 2.0 owners- and the cost was so tiny as to not even show up in their financials as significant. To-tesla cost of HW4 is likely just a few hundred bucks, and 5MP auto cameras are in the tens of dollars wholesale in bulk.
More importantly, it's likely not "hundreds of thousands of cars" as the take rate for FSD has always been fairly low.... and the bit you're missing is they'd lose out on the $15,000 or more in $ from the VAST majority of HW3 cars that
did not buy FSD yet.... because now they never would. But if a retrofit to "real" FSD was part of that 15k or more price (and only costing tesla 10% or less of the price) it'd be a no brainer to offer it to both old and new FSD buyers.
The issue would be if it's NOT as simple as just swapping cams and the driving computer in existing locations.... if you get to a point of needing new wiring, or new body panels for new cam locations, that's a whole other nightmare road they're not going down.
There is not standard of performance required for anyone not promised L4+ capability.
So, what happens to the pre-2019 cars? Tesla may find it cheaper to refund a portion of the FSD cost for the capability that is lacking. Lawsuits will result, but in the end the argument will be over how much they have to refund to people who did not pay very much (comparatively) for FSD.
I suspect they'd need to fully refund, with interest- as they won't have delivered on any portion of the promise at all... (there was nothing in there about L2, it was clearly L4 minimum).
That said-- all THOSE folks paid significantly less for it- and there's not a HUGE number of them either- so even with years of interest it still wouldn't be a material-to-the-companies-books amount of $.
They might also offer them some kind of sweetheart transfer/trade in deal as an option (the refund would have to be offered as well)... offering such an option might mitigate the lawsuits over diminished residual value of the old car at least