I don't think Spain can win this competition. This game pretty much said why.
They won't be able to pin the big teams back like they can a Costa Rica or Japan. Their full backs are currently not strong enough to do that. That means, despite the fact they will always have more of the ball, their attackers will need to creative in order to engineer chances. In a close game, chances are that a ball from midfield won't be coming, in addition neither Pedri or Gavi are that aggressive with their passing. They won't be able to break down, Brazil, France or even Portugal.
On the other end, France have Dembele, Griezmann and Mbappe who are very direct. Brazil have Vinicius, Neymar, Gabril Jesus, Richarlison and Martinelli ( who would be really dangerous against this Spanish defence). Portugal have Rafael Leao, but they also have the direct passing of Bruno, who would make things impossible. Even England, who I do think they would easily be able to pin back due easily winning the midfield batter, but they would still struggle to play against Saka, Rashford and Sterling. When Sane came on, his pace and directness completely opened Germany up. The chances were there prior, but Muller's lack of pace and Gnabry's passiveness were not able to exploit it.
I think this problem exists for a few reasons.
1. Busquets doesn't have the pace to cover those gaps around him.
2. Both Pedri and Gavi push up quite high. In big games, where physicality and quality can cut through the movement and passing of Tika Taka, there will be spaces in behind both. This is why Luis Enrique felt the need to bring on Koke later on.
3. Their full backs are aging. They can't be isolated on on one with a quick attacker. They won't be able to keep up.