It may change at some point, but you've probably noticed that Tesla make incremental changes at (seemingly) random times. Elon comes from software and that's how software is typically done in an agile environment. A feature that adds customer value is done, it is released. We see that obviously in the OTA software updates. But Tesla extends that philosophy to the hardware of the car itself.
A few years ago, we got the refreshed front hood and headlights. While it modernized the front end appearance, it was fundamentally the same car. AP2 was introduced in a "random" quarter. White Interior, ventilated seats, same way. AP2.5 was introduced when Tesla felt it was ready. Most recently was the new, faster MCU2. All incremental, but they obviously add up over time. Now the ventilated seats are back (hopefully improved!).
You say "It's been a while since Tesla has updated the vehicle"...well, since 2016 we have had 100kWh battery pack, AP2, AP2.5, new interior colors, new wheels, new seats, faster MCU, improved motors and other smaller improvements.
I think it is safe to say that Tesla is
constantly improving their vehicles...it just happens more incrementally and on a mysterious (to us) schedule.
Many are expecting to see a refreshed interior overhaul. But have been for the last 2 years. Maybe it will happen. Or maybe not. Maybe they will suddenly change the door panels one day. And then a month or two later, a new console. Then a quarter or two later...a new dash a la Model 3 and it's infinitely adjustable air vents. I'm not saying that they would incrementally update the interior rather than big-bang it...just that it is certainly a possibility that you can't dismiss based on their history.
The other big change people are expecting is moving to the new battery cells. While most of us believe this is an inevitability we just have no idea when it will come. My personal guess (and it's of course only a guess) is that it wouldn't be before Model 3 is humming along at 5000+ units a month. Because while Tesla would likely want to use the same cells to further build their economies of scale, they need all of those new cells for the Model 3 ramp. That's probably why they extended their contract with Panasonic for the older cells a while longer.
If you wait 6-12 months, you will likely get
something not available now. It could be relatively minor like ventilated seats or some new wheel option. It could be something more major like a new battery pack or maybe even significant interior changes. But you would miss out on driving the best car on the planet for the next 6-12 months and you can also be sure that the people who eventually buy
their Tesla 6-12 months after you finally get your car will get something even better ;-).
Suggest leasing
"Tesla will never stop innovating. People are buying the wrong car if they expect this. There will be major revs every 12 to 18 months." - Elon Musk