Is Ironic his replacement has not really been doing well, though ignoring his drama with Manchester United I think he should lower his wages for at least a season or two in order to prove he still in good shape to earn more because I think even Saudi teams won't really give him an high wage as he ought to have earn except he can prove he still got his skill in him.
De Gea has a salary value that must be paid by Manchester United is too big so the management decided not to extend his contract after negotiating a salary reduction.
But did not get a decision because De Gea himself still insisted on not wanting his salary reduced.
If you look at De Gea's ability, it was still quite good before his contract ended and he even became an irreplaceable goalkeeper at Old Trafford. The arrival of Onana changed everything even though if you look at the abilities of both of them I can say De Gea is a little better.
Rumors are circulating that De Gea is getting some proposals now and there are several teams interested in recruiting him.
But if he asks for a big salary, the Saudi Arabian League is much more capable than joining a European club with the hope of a big salary.
Sometime, we as humans, mostly sane individuals should use our tongue to count our teeth, and that is what I mostly expect from David de gea, but he is not doing that, since he left Manchester united he hasn't had a club he is plying his trade because his salary demand is too high, something that has really gotten me surprised, because he should have known by now that their are few clubs that can afford such high salary earner, and since such clubs aren't coming for his signature, the logical thing to do is for him to reduce his demand if he truly want to continue being a professional footballer, because for him to stay without a club for two seasons now, is absolutely disastrous to his career.
Lastly, just as you rightfully pointed out, it's only clubs from Saudi Arabia that would want to spend so much money on him now, because am quite sure that top clubs in Europe wouldn't spend so much on a goalkeeper salary right now, so the best thing he should do to salvage his failing career is for him to reduce is wage demands, so that smaller clubs can afford him.