That's like me saying, right now Margot Robbie isn't interested, but you never know she might break up with her husband so I'll hold out in case she does.
De Gea is delusional if he thinks he's getting a move to a big European club.
Again, it doesn't have to be a top European club. Just a better offer than the ones he's received so far.
The base point is that there's no harm in him waiting if he thinks that better offer might come along, because his stock isn't going to dramtically drop further between now and January.
Also, you support a top European side that within the last 12 months has brought in both Wout Weghorst and Sergio Reguilon, players who failed at Burnley and Spurs respectively, and wanted to bring in Marko Arnautovic. And it's not just us. Stoke/Newcastle failure Joselu currently plays for Real Madrid, Barca have previously signed the likes Spurs failure Paulinho and the awful [Irrelevant point], and Christ only knows how many piss poor player have found their way to top Italian sides over the years.
Far weirder things have happened than the likes of De Gea fluking his way to a relatively sizeable club due to circumstances. Players fail upwards
a lot in football even when they're still contracted to clubs, let alone when they're unattached.