I've been thinking about when the GOAT will retire. He has a contract with Inter Miami until Dec. 2028, but can obviously retire whenever.
I think there is a good chance that he could retire at the end of 2026, with his supposed dream to retire at the same time as Suarez (this guy is beyond retirement).
If he doesn't retire at the end of 2026 and he is in good physical condition (to which I think he will be), then I could see him play until the Summer of 2029 (which is when the MLS season ends). Also, if Inter Miami wins the Concacaf Champions Cup which will grant them access to the 2029 FIFA Club World Cup, then I can see the Mas brothers trying to convince Messi to play until then. Rodrigo De Paul having a contract until Dec. 2029 helps a lot massively.
There is the Jan - May 2027 MLS season, where he can win another MLS in a short amount of time.
There are also talks that Liga MX and MLS clubs can participate in the Copa Libertadores in the near future, a competition Messi never played before, so there's that too.
There is also the 2028 Olympics that will happen in LA so I'm sure there will be calls for him to play there (RDP hasn't played in the Olympics at all, so I wouldn't be surprised if RDP is asked to be one of the over-aged players). This is assuming of course if Argentina qualifies to the Olympics.
There is also the 2030 World Cup that will be played in Argentina and Spain, 2 of Messi's home. I would think that there is a part of him that desires of him to play the World Cup in his home country and in Spain. Could also be the only player ever to play in 7 World Cups.
Would be a crazy fairytale ending if Messi signs a 1 year contract with Barca for the 29/30 season, getting a standing ovation from every stadium playing as a super sub and then plays at the 2030 World Cup at the age of 43.
TLDR, Imo good chance that he retires at the end of 2026, but there are a few factors that would give motivation to extend his playing career.