It won't be super exciting instead it'll just be a retirement home just as china was before the football federation decided to do something about it and make the league unfavorable to foreign players just coming to china to look for money. Having the two best players in your league would definitely boost the league in regards to attendence of game and more sponsorship coming in but this two players aren't in their prime any more and won't be giving in their 100% most especially Messi since he feels he has nothing to prove anymore as he has supposedly won everything winnable in football (but that's not true, he failed to win some trophies in PSG).

Also I doubt if the news is official, maybe this is just an attempted by ESPN to get traffic as transfer wouldn't be announced until the transfer window is officially open especially high profile player like Messi. He's differently leaving PSG but I don't think he'll go to Saudi Arabia. I would prefer he returns to Barcelona as he has an unfinished business with them although it would look  somehow seeing Xavi coach Messi that he once played with.