Then what? taking advantage of Messi prime might be a priority but shouldn't be at any expense .
We won CL back in 2006,Milan won it next year and appearing in their 3rd final in 5 years.they kept their policy of signing ready player to continue their winning phase .we kept caring about youth with veteran player .we won 3 CL after.Milan doesn't look like a team that will qualify qualify for CL next year .and missed it for 2 years in a row now .Inter had same struggle after winning treble with aging squad
Imo, Italian teams are not a good example for this debate.
Milan crashed not because of their policy but because of a Italian laws in early 2000s since when Italian teams needed to pay much higher taxes then the rest of the Europe, and then they slightly started to overpay and eventually they fell into the debts.
Inter, well, they are the crappiest team in the world, who would never have won a scudetto (something like a modern Liverpool) if Juventus wouldn't have been involved in a fixing scandal.
Then a crappy Inter (crappy because they had the worst sporting project for the last 20-30 years) suddenly bought half of the Juve's squad and with Juve in Seria B, and with Milan in financial problems, they turned into a winning team, when their only opponents were Roma in debts (in debts for the same reasons as other Italian teams, when they overpaid for Batistuta and other players in late 90s and early 00s, and especially since the Italian laws are not friendly towards sport lately) and Lazio in debts.
So, Inter getting on top is something like Atletico or Sevilla now rulling La Liga because Barca would get relegated and punished and Real bankrupted for some reason.
Anyway, I am also for buying older player TODAY while we have Messi.
The fact is that .Last season out of the 14 players who played most games in the season .only 1 of them will be younger than 26 when next season starts .and our 2 signings aren't younger either .
Also every team need a backbone of the right mix of youth old and players in their prime even to win now in most cases
We can easily buy some younger players in the next 3-4-5 players.
We won't be buying 29 year old players season after Season.
About a right mix of young and older players, well...
https://en.wikipedia.org/wiki/2007_UEFA_Champions_League_Final
Milan in 2007:
-- Dida 34 years in that moment
-- Oddo 31
-- Nesta 31
-- Maldini 39
-- Jankulovski 30
-- Gattuso 29
-- Pirlo 28
-- Ambrosini 30
-- Seedorf 31
-- Kaka 25
-- Inzaghi 34
-- only 3 players younger than 30:
-- Kaka 25
-- Pirlo 28
-- Gattuso 29
So, a mixture of youth and experience is just one option.
There are a lot of options HOW to win a trophy.
For example, our possible team in 4 years (Champions league final 2019):
-- Mats 27
-- Pique 32
-- xx defender
-- Vidal 30
-- Alba 30
-- Busi 31
-- Raki 31
-- xx midfielder (or Turan 32)
-- Messi 32
-- Suarez 32
-- Neymar 27
-- add Bartra 28, Roberto 27, Rafinha 26, Samper 24
-- and at least 1-2 gems will pop up from our La Masia in the next 4 years
Still, a quite "young" team without any player older than 32 (compare that with Milan's winning squads).
But, it is a known fact that Barca's fans are slightly obsessed with youth in general, and that a younger player always looks "better" and with more potential than some player aged 28 or 30.
Also, as I have said, Barca can easily rebuild in only 2 years with 2-3 players each season for 30-40 Millions (some younger players like defenders, midfielders or similar).
About attackers, we will either have Messi until his age 35, so no need to worry there about a new attacker.
Or we will sell him aged 33 for 80-100 Millions and use that money for a new attacker.
So, basically, we have young Neymar and we will have Messi until his retirement.
Basically, the only "expensive" signing which we need is a XX player after Suarez, one day.
And possibly one midfielder.
We have enough of defensive midfielders in Busi, Roberto, Samper.
We have enough of midfielders and we will buy some over years (or produce some new midfielders).
And in defense, we can always just buy a bunch of Mathieu's and Vermaelen's aged 28 for 20 Millions.
So, our future doesn't look that grey even now, when we will have all "older" players.
We will NOT need that many players to rebuild one day.