Sounds like it really depends on how much of a "techie" you are. Mechanically, an EV's skateboard platform should be relatively trouble-free for 500,000 miles or more. However, what technical bells and whistles will grab your attention in the future and get you to "upgrade" to something else???? Using the computer analogy....if you were interested in basic word processing functions...and that's still really all you want to do, then a 1st generation IBM PC can handle all your needs a whole lot faster than you can type. BUT.........if over the years things like YouTube videos got your attention and you just had to have that new technology, then you've likely upgraded to a new computer every 3 years.
Cars follow a very similar trend. Some of us will probably keep a Rivian for 2 or 3 years before some new model catches our eyes. Others will be more than happy to keep a Rivian as long as we can keep it on the road and running.
Variety is the spice of life!!!! Enjoy the Rivian adventure!!!