In the USA, currently roughly 25% of light vehicles on the road are 20 years old or older [1]. The average age of light vehicles on the road is steadily increasing [2]. The current federal target is that 50% of new cars sold in 2030 will be electric [3]. I don’t know what you consider “common,” but with these data, I wouldn’t be surprised if 20% or more of cars on the road in 2050 were still ICE, and this doesn’t even take into account larger vehicles like busses and trucks, which tend to stay in operation for much longer [4].

If batteries get significantly cheaper, charging infrastructure gets significantly better, oil & gas pricing starts to include its environmental cost, and public transit becomes much easier for those that really can’t afford anything but the cheapest car, then all this might change.

One of the big problems with “ICE vehicles will become unaffordable”, is that the ICE cars themselves will get cheaper, and for people with less income, it’s the big upfront cost of electric cars that keeps them from switching. If a person cannot afford to pay for an electric car out of pocket (it tends to be difficult for poorer people to get access to loans and for loans to be available for older cars), then they will be forced to pay for gas at whatever price it costs.

[1] https://hedgescompany.com/blog/2022/02/how-old-are-cars/

[2] https://www.bts.gov/content/average-age-automobiles-and-trucks-operation-united-states

[3] https://cars.usnews.com/cars-trucks/features/will-us-reach-50-percent-evs-by-2030

[4] https://www.motorbiscuit.com/how-old-average-semi-truck-versus-average-car/