The new MCU update is definitely a huge bonus for these used Model X. As you mentioned, most of the used X available currently have AP 2.0. Even with the new MCU upgrade available, it's still very unclear how to deliver FSD with 2.0 hardware. Updating the MCU does not update the sensors or cameras on these cars, and I think there is still some uncertainty on exactly how they are going to achieve FSD with 2.0 at this point. There are reports of quite a few people with significant degradation issues specific to the 90 packs on Model X. I'm personally unsure about the practicality of the falcon wing doors as well. So take all of that, and compare it to a brand new Y for $10K less, that gets an extra 50 advertised miles, and I think there will be a lot more takers of a Model Y vs a 3-4 year old X w/ 2.0 and a 90 pack.