Fast forward to a summer of 2021:
Frenkie=here
Busi=gone
Raki=gone
Vidal=gone
Arthur=playing here and there
Basically, in 2 years, we will have one a half available midfielders.
Even if Alena will be a 5th choice, we will still need a choice no3 and no4.
Maybe even a choice no2 if Arthur will continue being injured and unavailable all the time.
Now, please don't reply: we could have Alena and Puig as choices no3 and no4.
That would be the worst midfield since 80s.
So, we will need 1-2 new midfield starters and 1-2 new squad players.
Realistically if Arthur can't stay fit for a season until 2021 he will be gone. So, there are two possibilities. He will either remain at Barca and be a starter (provided he keeps improving) or he will be gone.
By that time, Messi will be too old or gone. Suarez will surely be gone. Alba will probably be gone. Pique will probably be gone.
We are talking about a new era by then, so I guess we will need something more than a no3 and no4 midfielder.
That is why, we should already be looking for future starters and not current squad players.
I don't feel Puig or Alena will ever be starters for Barcelona. But if a no3. and no4 CM is needed, then they are decent enough and we don't need to spend money.
Except, I already said this, if Olmo is considered a future starter or high prospect, in which case we need all the talent we can get.