Indeed. Sell for around £40m, spend £20m on Van Dijk and we immediately improve the team with change left over.
Boss thing is we can buy his replacement before selling due to our wealth, so we don't have to show our hand early anymore.
VVD is just as liable as Stones is for mistakes - as every other defender is.
Stones should be the one we go all out to keep (as it does seem Rom is the one intent on leaving). If City do indeed come in for Stones - and he wants to join the best manager in the world at the moment - then that's perfectly reasonable and like you said, we'll get good money for him. But it'll be a blow.
I also think VVD would cost a lot more than £20mil, btw. He's on a 6 year deal signed a few months ago, and So'ton would rinse us every penny of the Stones money for him.