The RUC inequality between a hybrid and an EV is something they need to acknowledge. I'd recommend doing what I did and emailing (firstname.lastname@example.org) the Ministry to express your concern so they can hopefully make some amendments between now and 2021.
Yes, I'm going to be making a submission around this. A hybrid Prius effectively pays ~$38/1000km in excise tax, while a EV if nothing changes will pay RUCs at $72/1000km. This will result in having hybrids with lower initial purchase price, still a good subsidy, better range, lower battery replacement costs, and similar running costs to an EV. Thus it will make more sense practically and financially to own a hybrid than an EV which is the complete wrong signal when EVs are the much better option for reducing CO2 output.