A new battery costs $6k+, requires professional installation, and cannot be rebuilt at least not by a shade-tree mechanic like myself.
The "shade tree mechanic" (love that old farrier term) will eventually transition from wrenches, grease, oil, and piles of rusted parts to learning how to diagnose a bad cell pack, drop and open an EV battery, and remove/replace the cell pack with a new one. No oil and no grease involved. Just new equipment to raise the car and lower the battery. You'll still need those wrenches for the bolts holding the battery pack in place under the car.
There are innovative backyard mechanics out there already experimenting with the new fangled technology. It's fun to watch their YouTube videos and see how they circumnavigate the new obstacles of modern vehicles. They take it as a challege to see if they can triumph. My son, who loves to find the old cast-off "buried in the weeds for 10 years" type classics and get them running and back out on the road again (I stand in awe of his "wrenching" talent and knowledge) , has now expressed an interest in getting an early Leaf. About the 2012 timeframe. You could have knocked me down with a feather when he told me that. But apparently he's not alone in his age group at looking at the older, affordable EVs as their new projects. Problem is, there are scant few to choose from and the market on those is thin.
Batteries at this point are still pricy. I've read of quotes up to $12k to replace a battery. The old ones, even with diminished range, have value and are in demand because they can be re-packed with new cells to bring back the original range, or used as solar power banks since they are designed to charge and recharge easily.
I'm at 70,000+ miles on my 2018, and in 4 more years expect to be at 150,000 miles. There are a few maintenance things I'll need to keep an eye on (cabin filter, tires, lights, windshield washer fluid, 12 volt battery) but I suspect the original equipment brakes will still be basically new (since I almost exclusively use e-pedal driving) and shocks and suspension will survive as well. All my ice cars reached 150k to 200k, but by 90k they were starting to nickle and dime me to death with engine repairs. It's the little things that you forget about later, but annoy you with repairs (some fairly pricy) at the time. All those millions of pieces, including the cooling systems, needed for a combustion engine to work. It will be interesting to see if my EV reaches that milestone of 90k with only the tires needed to be replaced due to wear.
Surprisingly, I'm still enjoying the level of tech and comfort my EV offers, and very reluctant to give any of it up for a newer model. I do like being able to indulge my inner teenager now and then to hop in my car for a drive without worrying about gas or gas prices to fund my frivilous fun. Yes, I do have to replace the energy used, but I can get some of that for free at any and all free Level 2s in the area. Otherwise I have to suck up some of my home grown solar supplied energy for the car, which isn't much of a hit. A few pennies. Not anywhere even close to the $$$ hit from a gasoline station. Best part? No toxins spewed into my breathing air at any time. And silent. Oh, so blissfully silent.
However, I intend to keep my Prius, just in case I need to drive a long distance (gotta love that 60+ mpg) because the EV charging infrastructure is still building out. When the new infrastructure can comfortably accommodate my EV distance needs, then the Prius will find a new owner. But not before.