At the age of 38, of course Luka Modrić is no longer able to compete in playing in the top European leagues, so it is only fitting that Luka Modrić spends the rest of his career playing in the Saudi Arabian league to collect more money and also there the league is not competitive making him Luka Modrić can still compete in showing his performance, which is different if he stays at Real Madrid.
The Saudi Professional League is not that less competitive as many view them as but they’re already gaining ground and building their standards in football already. Luka Modric joining that league because he doesn’t wants to play a competitive football might be achievable if he’s not used more often on the pitch than he’s rested on the bench. If Luka Modric joins any team there, they’ll see him as a mentor and other players will be looking up to him in the field when playing. So we can’t be so sure he’ll be playing a less competitive football as the league is already gaining recognition globally.
Real Madrid only needs Luka Modrić to be able to guide young players so that there is regeneration in the Real Madrid team and he has been doing this for the last few seasons until now it is time for Luka Modrić to leave, either retiring or continuing his career in a non-competitive league. I think it's the same, those are two good options.
Luka Modric’s impact in the league cannot be overstated without giving him the appraisal he deserves for building the younger players. He has gradually been replaced by youngsters in the position he is playing from and how this young players play shows how impactful he must have been to them when they were under him practising. With the young players that can fit into his position, leaving the club won’t be any problem to the team since they’re fully in the squad.