The irony of this daft scheme is it relies for it's funding on people buying ICE vehicles. Then to add insult to injury, I'd say nearly 100% of those people buying an ICE vehicle would happily buy an EV if there was one available that either they could afford or fitted their needs. This scheme is an unfair tax on those that cannot afford an EV or have needs that cannot be met by an EV. This scheme isn't going to reduce EV prices to a level those that cannot afford them now will be able to afford them once the daft scheme is introduced.
So far as vehicle pricing goes that will take care of itself. As EV's become mainstream they will become cheaper and ICE will become relatively dearer. The ICE will become dearer for two reasons, ever increasing emission standards will increase development costs and as production numbers reduce the normal production costs will amortised over fewer vehicles. There is no need for the government to interfere when natural progression will achieve the same result.
I find it incredible that EV evangelists that think just because an EV suits their needs, an EV will suit the needs of everyone, therefore it's OK for the government to penalise those naughty people with an ICE for not buying an EV.
Personally I think the RUC free ride EV owners are getting is more than enough recompense.