If it's about externalities then there is a ceiling on the taxes. Because combination isn't infinitely bad.

If it's about revenue, taxing combustion engines gets less attractive the smaller the market becomes especially if it's easy to switch.

And if it’s about revenue, which is obviously the reason why the tax exists at all, what we’ll see is that the taxes will follow the money . They’ll find a way to increase the tax on the use of electric vehicles.