Now days car manufactures pay BIG money for 'placement'. This does not only apply to car maufactures: watches, drinks, hotel chains, airlines, anything really. Hence the reason Bond drive a BMW in some films.
So it will be for Aston Martin to pay for the next placement in a Bond file.
In the '60, when the proper Italian Job was filmed, the film company had to pay for its own minis. No discount was given.
So, sadly I can not see MMC ever having the cash for a Bond film.
