50% EMVs in 20 years is possible. EMVs need roads. So, either you tax the vehicle's road usage (*beacon monitoring miles traveled -- sounds bad), electricity used for recharging (*that will be easy to cheat) *or* the road funding comes from some general fund -- everyone pays.
For free you will get a 2 track path that turns to mud -- 1919 style. Or, every road will be a toll road and you use your ATM card of prepaid 'toll card'.
It will be a new tax whether you like it or not. If you don't like it -- walking is good exercise
