I don't think it's likely for quite a few reasons. Maybe not each as strong as the other but still. I won't put "morality" in there because as we know footballers are lying, thick as shit planks like Henderson and do sell their morals once a threshold is reached but there are plenty of SELFISH reasons for players to not go:
- Prestige. Most young European players dream about winning the champions league. Without that dream why even play football?
- Location. Playing and living in London, Madrid and Manchester is surely a more attractive lifestyle than Saudi.
- Discipline. Although rich footballers will obviously have a LOT of leeway there, I would be nervous particularly if I had family - to be asking your young daughters and your wife to move to a rabid patriarchal society even for insane money is a tough choice. The alternative being they stay at home in whatever country, but then you're on your own.
And from the Saudi perspective it will be a money pit at first, much like China the financial losses will be staggering. You can't suck up premier league wages without premier league TV deals forever. Maybe people will watch the Saudi super League - I wouldn't do it for free.