De Gea is still top class. Those old enough will remember Schmeichel making some glangers and having stretches of poor form, but he wouldn't be overly doubted because his core talent was always there.
De Gea still has so much to give and it's going to hurt if he leaves and we watch him have an amazing decade more of football elsewhere.
Even if De Gea wants to leave and that happens, i've still seen nothing that suggests Henderson is the right person to replace De Gea.
Henderson seems like a decent keeper but is that what United should settle for? Is Henderson the only other option? No he isn't.