He also didn't say it would be worldwide or initially available only in certain countries (eg USA only).
How can buying FSD be better than leasing it when you never actually own it? It is a lot of money that hopefully stays with the car but does it? When you sell it can we be sure it is transferred to the next owner and if you part ex to Tesla, they are liable to delete it from the car when re-selling so hardly going to pay the extra in the part ex price are they.
If the car is sold to a third party it stays with the car. If the car is sold to Tesla, they can do what they want with their (after they buy it) car and leave or remove it before selling it on. If they don't appropriately adjust the price they offer for a car with FSD then it may be better selling it to someone else.
My car's on PCP, so no real value to me buying it in it's present state, and long odds on it being improved enough to be worthwhile for long enough too. So rental makes a lot of sense. But I notice he doesn't give a year, so I'd not be holding your breath.
Personally I doubt subscription will be available in UK until City Streets (i.e. current FSD beta) is released here also.
We're going to find out how long Tesla think you are likely to keep the car for. Four years and £150/month would be worse value than buying AP outright, three years and it's £190/month. TBH, on a long journey I might consider activating it for a month at £150 when it works in the UK, but I wouldn't bother day-to-day. More than that then I'd just do the driving. I strongly suspect they're looking more towards the £250-300/month bracket in which case I'll never go for it.