It depends on the club and their manager, really.
Debuchy was never in Arsene's plans like Di Maria was not in LVG's, but he refused to sell to United.
Moratta is not in Real's plans but still they didn't budge on their asking price when we tried to sign him.
We could have done the same with Di Maria if we wanted and bearing his wages wouldn't have been such a difficult thing for a club like ours. Just to teach him and PSG a lesson, if we wanted to.
The fact is, Chelsea want to offload Matic and they will sell to us if we pay the right price.
Jose even allowed Cech to be sold to Arsene. Reasons are different but the sale is a fact.
Lastly, my point is that Chelsea will not stop doing business with us because we signed Lukaku.