I think I just figured out how Tesla will retrofit all cars to HW3 (or 4, or 5) without losing money! Simply wait until MCU dies, then claim you have to pay for MCU replacement (at whatever price they set) in order to upgrade to HW3. They apparently already do that with drivetrain warranty, if your MCU is not 100% functional, drive unit is covered, but you have to pay $3K to fix your MCU first before they honor drive train warranty (see
this post). So, all Tesla has to do to retrofit your FSD for free is set an appropriate price for the MCU replacement to cover FSD. Given that FSD will not happen for years, almost guaranteed your MCU will die, and yes, even MCU2.