I’m so very sorry to hear about your son, that’s so tragic.
Thinking back to the cars I’ve had on the scheme, I’m with you, nothing has ever gone down in price. If anything it’s been pulled from the scheme after ordering to thankfully the order still stands. That was in the days where you diddnt have to wait a year only to find the model has changed so much that the dealers wriggle out of the contract.
I did have a Nissan Leaf way back when they were the old shape. I remember the dealership knocking the AP down from about £2500 down to £499 for the Tekna spec. I would never have afforded it otherwise. Great car but dreadful range. In the real world it was about 90 miles on a full charge.