I think people are jumping the gun a bit.
The cost for people to buy a Tesla has not changed. It is the same as it was yesterday, and for the past however many weeks since the last price hike.
It was £40,490 (SR+) or £46,990 (LR) yesterday, and it still is today. There is rumblings about the price maybe changing but it hasn't happened yet and they're taking their sweet time doing it if they're going to.
The only difference between yesterday and today - is that Tesla are swallowing the £3,000 loss from no longer being able to register the cars on the Government portal, to claim the grant. Customers never saw that money, and it was baked into the price displayed on the website. If you had an order agreement/final invoice for a SR+ or LR it would've said the cars cost £43,490 and £49,990 respectively, before the grant.
So - it shouldn't affect leases, at least not for Teslas.
EDIT: Obviously if Tesla bump up the prices between now and tomorrow, then it'll be clear that they aren't happy to eat that loss!