I think cristiano ronaldo will retire from saudi arabia league. Because I don't see any chance of coming to any European club with the performance of Cristiano Ronaldo. Also, the Saudi league will become very competitive within a few seasons.
Cristiano Ronaldo is going to be 40+ after ending of this Saudi contract, but he could be brand ambassador for this until 2030 World Cup or may be position could be changed as well from here, but his target is AFC Champions League and Saudi League title could be also achieved which will give him good stance before retirement even right now nothing is clear but most chances things could be under control for him with huge amount of money, and then he can live as any soccer club owner as well as we have many players right now.
But, soccer could be remembered him with his services and all achievements which he has done in last few years as one of the legendary players just because of him now Saudi League is also achieving many big things which will help them in future as well for the best.