I doubt he won't play the 2018 wc. He's devastated right now. And also mad, because AFA is a goddamn mess. Messi isn't one to complain, but complained against them on his instagram, a few days ago. And one of their directors made up to the press Tata was resigning after the final, hours before the game, to hurt the NT. Imagine that. sadly the NT is not a good enviroment for a long time. It's the same with Brazil. And it's so sad to watch, because it's 2 of the biggest nt's.
He'll probably come back for russia. Unless the worst happens and fifa really disaffiliate AFA, as they are threatening to.
About bad FA's, it seems that more or less half of the world have bad FA's, corrupted presidents and similar.
About Messi and a WC 2018, I just don't see what "good" can come out of it, except that he will remove some dirt from his name (from people who call him quitter now).
Majority of people agree that Argentina's team is weak and that Messi plays 120% to get them to semis and finals.
So, these are scenarios in 2018:
1. Argentina gets knocked out in group stage:
= Messi will be blamed by Argie fans
2. Argentina gets knocked out in 1/8s or quarters:
= Messi will be blamed by Argie fans
3. Argentina gets knocked out in semis:
= Messi will be blamed by Argie fans
4. Argentina gets knocked out in a final:
= Messi will be a guy with 5 losses in 5 NT finals
The only win-win option is:
5. Argentina wins a World cup:
= everything is perfect
Now again:
1. Messi will be 2 years older than today
2. Argentina is not good enough. Except if they will magically improve a lot in 2 years to be good enough to win a WC
3. Their FA is corrupted, and it won't resolve that soon
4. who could be a good/available coach for them who can lead a team to a WC glory?
5. also, add enormous pressure on Messi in these 2 years until WC 2018, and pressure if they lose it again (which will happen 99% probably considering all facts around Argentina)
So, on one hand, haters will call him a quitter now.
If he'll play in 2018, he won't be called a quitter.
But what after 2018?
Fans will again attack him (since they won't win a WC probably).
And if he quits then, what then? He will again be called as quitter and NT loser, by his haters.
I don't mean anything bad, but I just don't see what good can come from him playing at WC 2018, considering all facts, Argie's fans expectations, pressure until 2018, and a possible disappointment after a WC in 2018.
I am really not sure if anyone can handle that amount of pressure and fan's disappointment.
I can see Argentina's fans asking from him: come on, play one more Copa. One more attempt... Then one more, then his last WC aged 35, as his last chance.