The Brazil international was a fringe player under manager Erik ten Hag earlier this season. He faced a similar situation after Ruben Amorim took charge.
However, the midfielder's fortunes have changed over the past few weeks with Amorim personally admitting that the 33-year-old had made vast progress.
Despite this, the former Real Madrid man could be on the move this summer if United are unable to lift the Europa League title this campaign.
Casemiro is one of the highest earners in the squad. His basic wages could rise to £300,000 per week if United qualify for the Champions League by winning the Europa League.
On the other hand, the club could resort to cost-cutting measures if they don't qualify for Europe. This could pave the way for Casemiro to depart in the next transfer window.
He could be sold for around £15 million.