It's difficult without a lot of money..in hindsight, not spending that money on Ferran and Raphinha and putting it all into a top DM candidate like Rice would have been ideal. But hindsight is 20/20.
The problem is, there is not many obvious solutions on the market. The few that are 'proven' or consensus top talents will cost huge amounts of money.
Everyone there is basically a gamble, so we will have to roll the dice in some way on someone, whether that be Zubimendi, Amrabat, Redondo etc.
Brozovic could be a really good option for a couple years, very cheap for his level and could improve on Busquets even.
It is difficult to replace every quality player tbh.
Any proven WC player in any position, will cost at least 50M at your lucky day. That is what Kounde cost us, and he was the closest thing to proven commodity when we signed him as Pique's replacement.
At the end of the day, you must take calculated gambles, there is no way around it.
Whether it is a short stop gap, a free agent with question marks, a good player who hasn't been tested enough at top level or an overpriced player, or maybe a young one.
Last summer, every transfer we had, had many question marks, but other than the last day free signings (Alonso & Bellerin) I would say each one of them improved the team, and played integral part of our Liga title run (maybe with the exception of Kessie) .
It won't be easy to replace Busquets, but the market is full of good players at the right age who are starters in European top flight who are ready for next step (Ugarte, Zubimendi, Amrabat, Florentino Luis, Neves, Caicedo, Rice) or younger players (Redondo, Lucas Gourna-Douth, Diaz, Latvia, Ugochukwu, Varela , Vermeeren etc) and some veterans like Brozovic or Kante.
I don't know how good many of those names btw, and many of them I don't like.
But it is up to the club to get the player who can improve us with our financial abilities.
And tbh, I trust current board to do so, but I don't trust them to get the best option.