The easily farmable land is already in use. They can grow more using irrigaion and fertilizer, but the resulting food will cost more than Africans can pay.
Perhaps the Chinese will come in and play “cowboys and Africans”?
Probably.
They will be ruthless in ways the Indians and Europeans will not, and no one will criticize.
The Africans will end up as slaves in everything but name only.
But it’s either that or regular overpopulation / starvation cycles for them.