That will depend upon to whom he has bequeathed the shares.
It's not uncommon though for a shareholder agreement to be in place which would allow other major shareholders to acquire his shares. I'm pretty sure the Board will want to retain a majority holding.
Anyway, I'm sure he'll be around for a good many years yet.
So how much is your bid at Blackstone Sington should an heir decide he/she isn't interested in their allotment of the shares?