It's highly probable that Messi will renew his contract with PSG for additional one or two years, after that he might come to Saudi Arabia. Messi in his 35 is different from Ronaldo as Ronaldo didn't find good deal in Europe and that why he preffered Al-Nassr, while Messi will be offered great deal from his club. The numbers Saudi teams are paying look big for sure, but I think players take other factors in consideration when they think about a deal. However, Messi will still has a chance for such salaries even after one or two years.
If Messi is hoping that he may end up with the same contract after 2 years, then he is wrong. Right now, Al Hilal want a superstar in their squad to counter Al Nassr's Ronaldo and that is the reason why they came up with this astounding offer. Once Ronaldo retires from club football, Al Hilal may not be willing to splurge such huge amounts. IMO, Messi should take up this offer and move to Al Hilal. He is 35 years now and at most he has another 3-4 years to make some money for himself. Once he retire, his market value will vanish. He has played top level football for well over a decade. Now he needs to focus on the money part.
messi is very different from cristiano ronaldo, if you notice that messi plays in a position that allows him to do many tasks that the specific players of that position cannot overcome messi, messi's passes are very precise, messi manages to coordinate the entire midfield and in attack until the goal entry, while cristiano ronaldo is only good at dribbling and scoring goals, something messi can also do very well, in this new club that cristiano ronaldo was, he will be useful if he manages to score a lot of goals
but if messi was at this club he would be much more useful due to the way he adapts on the field, but messi doesn't need to go play in these arab clubs, i even believe that messi after PSG he will retire, because it seems to me that he is the type of person who knows when to stop and is not looking for fame and money at all costs. ronaldo was already in retirement time, but he chose to self-destruct