I fully expect road tax for ICE vehicles to follow this pricing method in years to come.
I don’t think that it would make any sense for the government to do that. They’d be removing something that you simply cannot avoid or fiddle (fuel duty) and replacing it with a system that is a major admin burden and would require checking. It makes far more sense to leave fuel duty on petrol and diesel and apply a pence per mile charge to EV and PHEV drivers.