I am going to be a skeptic here ... no way they will stack up the three rebates in a such a way basically giving you essentially 40% off the car price. I will believe it when I see it.
Just because the 14K is already unprecedented, I believe, in any country applying some sort of a rebate (don't count Norway, which taxes heavily gas cars ...). So for them, to go as high as you pointed out, it would definitely pour more gasoline into a fire of a province bleeding left and right. I know it's a spit in a deficit bucket with EV ownership sitting where it is, but .... a) it's a principal thing for many ... b) Ontario doubled their EV sales from 2016 to 2017 ... we know all why that is for 90% of buyers, so in another works 14K is working, keep any other rebates to fund the road infrastructure funded by a gas tax, I don't contribute to.
What I am trying to say, is that any further EV vehicle rebates are not really necessary. What is necessary a dramatic improvement in the EV infrastructure, so that is where this Ontario government should be putting serious money in. And that includes, fast charging and apartment building, mainly the old ones which require some form of not so inexpensive retrofit