Biggest long term maintenance expense in an EV is battery replacement, which best estimates right now put the industry at roughly a 15-30 year replacement rate. Depending on how you finance it, a battery replacement should be doable for <= $150/month average, and that's assuming a full replacement. (Depending on one's range needs/usage patterns some people might be able to make 20-50 years on the capacity degradation curve of a vehicle's original battery before needing a replacement, given current evidence.)
Electric motors have way fewer moving parts and fluids and currently are generally expected to outlast any car frame they are put in.
Most EVs advantage regenerative braking so break maintenance cycles are also longer to comparably sized ICE vehicles.
The other maintenance risks are the exact same between an EV and any other car, things like: HVAC, plastic degradation, rust, and accident damage.
The one unique Tesla risk on a 15-year horizon is their software updates. Their penchant for over-the-air software updates is handy in the short term, but possibly a risk in the long term lifespan of a vehicle. Though that's a risk Tesla would hopefully be incentivized to avoid (for bad PR at least), and possibly a mitigatable risk.
Most cars have a vigorous service schedule that is an endless sea of tire rotations, brake servicing, oil changes, belt replacements, among all of the unexpected maintenance of thousands of moving, wearing parts.
A Tesla or a comparable EV, in contrast, is a cartoonishly simplified variation with magnitudes fewer parts and maintenance needs. The probability of an EV requiring less maintenance than a ICE car is 100%.
Of course right now those EVs come at a premium, but as they hit the mainstream this is going to be a critical differentiation.
Same! Mine's a 30 year old Volvo wagon and a 32 year old sedan. Besides oil changes, I've spent about $2000 in the last 5 years of ownership. I was only left stranded once, but that was because the NAPA in the middle of Nebraska didn't have the part I needed to get back on the road. I would doubt that the same NAPA has many Tesla parts in stock as well.
If Tesla is to ever have the same reputation, it will be because they made issues trivial to diagnose, dead simple to replace and allowed other manufactures to make replacement parts.
However, this whole argument is moot, because the era of the 15-30 year daily driver is over anyway. When my ignition computer failed, it was $35 to swap one out from a junkyard. You just have to unplug the old one, and plug in the new one and off you go. What's the procedure for replacing a computer on a 2018 Tesla in the year 2038?
Furthermore, any new car has little maintenance to really worry about within the first 100k miles. If you are upper middle class in a bougie area, you're probably buying a new car before maintenance is really an issue anyway. (cue everyone chiming in that their Subaru's turbo blew up 100 miles outside of warranty)
I drive a 15 year old Volvo wagon that almost never needs service :)
Of course I exaggerate - I probably average $150/month in maintenance. Sorry, but the chances of Tesla doing the same over 15 years is zero.