I think no petrol/diesel car sales by 2035 is a dream, as we know that big countries are still investing in petrol and diesel mining so if there are no petrol/diesel cars then petrol or diesel sales will drop, especially since switching to electric cars also requires almost the same power or cost. Moreover, even now in developing countries there are still many homes that do not have electricity.
It is not possible to say what other countries will do but banning petrol/diesel vehicles in my Bangladesh will not be possible at all. We are always plagued by the terrible curse of loadshedding, so if we have to find alternative vehicles to petrol or diesel, there will be pressure on electricity which our country Bangladesh cannot control, as a result mill factories will close down. So it is not at all possible to discover or import any alternative vehicle to petrol in Bangladesh.