The Argentina team will have to prepare the team without Messi and Di Maria for the next World Cup. Because the chances of both of them playing in the next World Cup are very low.
It's true that Messi and Di Maria are of course too old to participate in the 2026 world cup and that is an opportunity for other young Argentinian players to fill those positions soon. Maybe at this time with the existing Argentina squad it is still possible to continue moving forward, but the role of Messi and Di Maria as creative figures in the Argentinian attack line will be a serious problem if there are no replacements. Maybe in a year or two, new Argentinian young players will appear, coupled with the current squad they will try to defend the world cup title.