Argentina is a great team developing itself in these last years with Messi as an even greater team,they lost the final of the World Cup in 2014 and they won it in 2022 so their form was excellent and it was the best team of the whole World Cup.In the Euro though France yes it is the most promising team to win the Euro but let's not forget Germany who is the host and is playing in front of their home fans willing to ask a forgiveness for what they achieved in the last years and wanting to be one of the most prestigious teams like they deserve too,then of course England is the best team,let's also not forget a very young age as a team for Spain who are growing together,I think it will be disputed between these teams the Euro 2024.
Argentina will survive without Messi. They have good depth in player pool. But I can't say whether they will be able to defend the trophy in 2026 without Messi. They have a very well balanced team with youngsters like Julián Álvarez, Nicolás González, Alexis Mac Allister and Enzo Fernández providing enough support to veteran players like Ángel Di María, Rodrigo De Paul and Messi. France also have a similar setup, but then the ci-ordination between different payers is not that great. Argentina on the other hand has excellent team cohesion.
I am not sure if they will be as good, but they already won a world cup so I do not think that it will matter all that much. They do have a decent number of players but I do not think that they are good enough to win anything anymore, it's not just about Messi or not, you can put a 30 year old Messi into this club and it would still be hard.
It's a marvelous achievement that they won the world cup, it was definitely a great success but I do not see their team talented enough anymore, they just do not look like it to me. Maybe I am mistaken, after all they won the world cup title, so they must be good, but to me the roster itself is not that amazing, look at the roster and valuations to see what I am trying to say here.