Grant is set to lose Michael Essien, Mikel John Obi, Salomon Kalou and Drogba - but has hinted there may be moves to counter the losses in the transfer window.
"It's a big problem," he said.
"I don't know why the Euros are played in the summer yet the African Cup is played during the season - when they know most top African players play in the European leagues.
"They are four good players, so this is one of the reasons we have a big squad. Maybe if we find someone good for Chelsea, we will take him in January."