Of course battery technology will only get better. Batteries will get lighter and more energy efficient. Having owned a Tesla for the last three years. Each software update has the potential to do/deliver great new features. So I think Rivian will do the same. As for their mechanical improvements. Its a fairly advanced vehicle now. What more can you want mechanically. In addition, what percentage of Rivian owners will TRULY go crazy off-roading with a $90K vehicle. I live in SoCal and I"ll definitely do the LA-Mammoth run but I doubt I'll go offroad more than a handful of times.
Mechanical upgrades will likely happen iteratively and on the fly, kinda how Tesla does their vehicle updates. There will always be that next bit of modern tech in the pipeline that you could wait for. For now it's in-house motors, 800v architecture, and I'm sure they are working on other cool things under wraps. Some of these may even exist on the R1T by the time people on this forum take delivery.
That is certainly a risk but it applies to every vehicle. I think it's a greater risk with newer vehicles but if you let that get in your way, you will never make the purchase. Nothing is static.
I’m confident the 2025 R1T is going to be a better vehicle than a 2022 model. In house battery pack with better technology, 800v architecture, heat pump, in house designed Enduro electric motors, etc.