I did a comparison between the Model X 90D I bought on 2016 and a similar version I can configure on 2019. Even with the phase out of federal tax credit and some inflation of option like 6 seat got bumped from $3000 to $6500. The total prices does get cheaper by $5000, this seems to be a better deal especially I was only getting a 90D with about 250 miles range while the current long range can go up about 328 mi.
But there is a caveat! I didn't include the so-called "Full Self-Driving Capability", which costs another $7000. If we don't factor in the promised feature like "Recognize and respond to traffic lights and stop signs", it does pretty much the same as AP2 auto-pilot can do, like "Navigate on Autopilot, Auto Lane Change, Autopark, Summon". With $7000 added, the latest version is $1525 more expensive.
Personally I don't feel that bad and I will probably swap my current one once it hits 4 years mark but no sure what others think.