You can't replace 11 players in 1 year. Start with Rojo, Darmian, Pereira and Valencia, who offer nothing. Add Fellaini and that's a lot of wages and spots in the squad. 5 additions in 1 year should be possible.
My list was as much an easy pick list, as anything. I think you could change that much if you did it over January and the Summer, especially if you are replacing with fresh talent.
But you are right it's a lot and balancing that out you would probably hold on to Lukaku for another year if you can keep him happy.
Young could be worth another year for his wise head with winning experience, still decent energy and fairly utilitarian like use. Darmian for all the critique is actually a half decent backup option who can play multiple positions and probably not at and outrageous cost.
I'd love to have Mata for his personality, but you cant spend over £100k a week just for that and I'm not sure he has anything on the pitch any more.
Aa with all these things it really comes down to who wants your players and at what price. If a club didn't want to pay Sanchez more than £150k and without a transfer fee we would be left having to subsidise the £200k extra in his salary and of that's the case and that extra money is sunk you'd be better of keeping him.
If someone would take him on a free and pay his demands I'd say let him go. Don't think it would have anything other than a positive impact on the team given his limited input.
I think the 11 I mentioned would be fairly low risk to flip out with new players.
Fred is one you probably need to give more time to and maybe Perriera.