Messi's current contract expires after the 2020-21 season. However, it wouldn't be surprising if he forged an exit before that after Barcelona's 8-2 Champions League defeat to Bayern Munich laid bare how dysfunctional the club is on and off the pitch.
Messi might have turned 33 in June, but he could probably name his next stop, such would be the demand for his services. Although the six-time Ballon d'Or winner is on the wrong side of the aging curve, he remains capable of pulling off incredible goals.
The Athletic's Adam Crafton wrote that match analysis from a 2017 El Clasico showed how Messi was being more economical with his movement:
"In the presentation, they focused on a match between Barcelona and Real Madrid in 2017, when Messi walked for 83 per cent of the five miles he covered in the game. Traditionally, football coaches would consider this to be inadequate from a leading player but using Metrica data, Fernandez and Bornn were able to demonstrate how Messi identified 'high-value locations' to create possibilities for Barcelona. Bobby Gardiner, a data scientist at a leading European club, wrote an article interpreting the research and concluded that 'in 66 per cent of the moments Messi won control of valuable space, he was walking. Even while strolling, he is helping his team by holding ground in valuable areas, waiting for the ball to come to him.'"
Even assuming Messi is past his prime, his time as a world-class footballer isn't over.
Losing Messi would obviously be a devastating blow to Barcelona, both in terms of the playing squad and what it would mean on a symbolic level. The Argentine star has spent his entire professional career in Catalonia. His transfer would represent a significant rebuke as to where he believes the club to be.
To some extent, selling Messi on might be the kind of shock to the system Barcelona requires to make meaningful changes.
"Coaches and players follow one another, but it has been several years since we have been able to be competitive on a European level," Gerard Pique told reporters after the Bayern defeat. "... The club needs changes. And I'm not talking at the level of the coach or the players, but structurally the club needs changes of all kinds. We must bring in new blood to change this dynamic, and if necessary, I would be the first to leave."
The 8-2 thrashing at hands of Bayern follows a 4-0 loss to Liverpool in the second leg of last year's quarterfinals and a 3-0 collapse at the hands of Roma in the second leg of the 2017-18 quarters.
In recent seasons, Barcelona remained near the top of La Liga thanks in large part to Messi's presence. Their reliance on him then gets exposed in the Champions League.
As long as he remains at the Camp Nou, the problem might persist.