While it might be the case that today’s EVs will not be economically longer-lived than 15 years, the overall average age of a car in the US is 12 years, and most of my cars have been bought with 10 or more years on them as it makes for very inexpensive motoring (no need for collision or comprehensive insurance, no financing interest, and nearly no depreciation).
I bought my 2015 LEAF new and suspect it will not be economically viable in 2030 while our 2005 Honda CR-V is 16 years old now, still going strong, and most likely will still be in service in 2030.