If he'd tested positive a few weeks ago maybe we'd have better chances to win the league.
Also, is he out for Euro? He'll most likely still be a starter next season so getting some rest during the summer wouldn't be bad. OTOH we've seen what impact covid had on some players so I'm affraid he'll be even worse next season and we'll still have no real alternative to him.
No. You can not replace Busquest because his replacements are way worse.
Btw,
72% - Sergio #Busquets 🇪🇸 has won 88 of his 123 international games for Spain (72%), the best winning ratio between the Spanish players called to play the next European Championships Finals with at least five games played. Essential https://t.co/2tfbuFCQUQ