For vehicle financing, I would expect finance companies to build in a balloon payment to the equivalent of the expected rebate if they are financing 100% of the purchase price, similar now to a "GST Clawback" they do on commercial hire purchase / loan contracts. i don't think this can apply to leasing so it could end up just being a cash windfall to the lessee (they are afterall the "registered owners"), but I would expect that residual values will be written down significantly reflecting the value of the rebate (which may actually push lease prices up) on real world vehicle values.
This will be a good move for new entrants to the EV market, but those who already own one have just seen the value of their vehicle drop markedly..