Looking to the future, Messi really needs a preseason with focus on his physical. Technically he's still the best, but his speed and stamina are limiting his technique.
Messi needs to understand that he's not young anymore, his physical abilities tend to decrease, not the opposite. We know he worked hard to have GOAT technical skills, but his body was helping him, with that outstanding speed and incredible agility. Now, his body is suffering the years of high competition and he needs to put extra effort to have his body in high level again. Also, he needs rest. He's 31. He needs to realize that and stop playing every little game.
He lost a bit of speed, needs to work on that, maybe lose some kg. His stamina wasn't a problem years ago, but now is becoming a huge liability, needs to work on that as well. In my opinion, is the best that he can do.
Apart from that, his teammates, both in Argentina and Barcelona needs to step up. Messi has his flaws and needs to work on that. But is worrying that Barca and Argentina were/are unable to realize his flaws over the last years and can't build a team to cover that. Both teams had Messi as their best player and both did the same: bring more responsibilities to Messi and let him solve the problems for him and his teammates.