Future scenario perhaps like this (in US$) for Chelsea in the next summer :
Hazard to Real Madrid, Costa to China ==> I imagine US$ 150- 200 millions for both of them....also releasing big wages players
Buy Lukaku ==> US$ 100 millions
Buy Sanchez ==> US$ 40 millions
Clean some dead woods : Terry, Cahill, Ivanovic ==> This trio still can play in massive wages at Europe or China ==> US$ 30 millions + also releasing big wages players
I predict they can also sell Cesc or Pedro ==> US$ 20-30 millions + also releasing big wages players
So without consuming yearly budget transfer, Chelsea perhaps still have US$ 40-50 millions...added by their yearly budget minimal around US$ 50 million...after having Lukaku and Sanchez, they still have US$ 100 millions to spend...
Scary....I don't even think Lukaku will be released by Everton more than US$ 50 millions...