De Gea's contract with Man United has officially ended. And currently, de Gea is a free agent. Yes, Man United did not renew the MU goalkeeper's contract for several reasons. However, because he is currently a free agent, Man United can actually re-sign a contract with him. But I don't think this will be done by them. Moreover, they are currently eyeing several good and quite young goalkeepers like CostaCosta, David Raya and others
Man Utd is keeping De Gea pending simply because they are hoping they can seal the deal on Onana from Inter. If it isn't successful, they might recall him back to the squad. De Gea has had a good run with Man Utd. I personally believe it's time for him to set sights somewhere else - probably in a different league other than Premier League and see the rest of his career there. Even Man Utd fans especially the ones I know personally wanted him gone 2-3 seasons ago.