No.
La Masia should be supporting the rebuild, but it shouldn't be about it.
In addition, it is also time to realise that rebuild isn't just a youth movement, it involves getting players in their primes and even a selective number of veterans.
Our most successful rebuild (one of the greatest ever) was done in 2003, and half of our squad was players signed aged 27-28 years of age. There was some younger guys (Eto & R10 was 23 when signed, Marquez 24) but there was other veterans like Larson.
VV, Puyol and Oleguer was the only starting players in 05/06 season CL final who played in Barca B/La Masia. Iniesta and Motta were other 2 players coming from the bench that season while Xavi and Messi had their season ended early on. Playters like Puyol and Xavi were in the teams for 7+ years at that point, Messi and Iniesta were the only youngsters developing in the team atm and Oleguer and Motta were Barca B players signings like Araujo.
Even with Pep retool, huge part of iot was about using the established La Masia players through the years (Messi, Xavi, Puyol,VV,Iniesta) and added only 2 players through 2 seasons (Busquets and Pedro) while doing 5+ important signings (Alves,Pique, Keita,Mascherano, Villa)
Last successful retool was with Lucho, and it was solely based on adding players from outside, with some chances to La Masia busts we were excited about like Munir and Sandro, who had a comparable performances to Puig for example.
At the moment we have no established La Masia players, there is huge gap between last La Masia veteran (Roberto) and the next one (Puig/Araujo/Fati)
If this is going to be successful rebuild, it should be done by shrewd signings, that makes those youngsters develop in their proper timeline with less pressure.
In next season, the only players from this squad that will be 24-28 (players normal prime years) are Umtiti,Lenglet,Dembele & FDJ. Only reliable player out of them is FDJ and the rest should not be even here.
In normal circumstances, this needs to be 10+ players, with at least 5 reliable starters.
I don't disagree with your point but the problem is players in their prime these days are either totally off the market (key players in other top clubs that don't want to sell them) or very expensive. Either way, in our current situation unlikely to get them. How much would 23 years old R10 or Eto'o cost today? If R10 would play for PSG we could forget about ever getting him (at least while he'd still play on top level).
So our only solution is to look at players with expiring contracts either this year or next year which we're doing. And that's why I'm not against signing Memphis. He won't be our R10 but could be like Giuly. And why I also wouldn't mind signing Wijnaldum even if he's on the wrong side of the 30s but still think he could give us 2-3 solid years. Garcia will also surely sign but he's another youngster.
But for other players who could we get this year?
- Alaba has apparently already signed for RM and if that rumoured contract - 5 years with around the same wages as Ramos - is true I'm totally ok with us staying away from him
- Draxler could be an option for midfield but I prefer to give a chance to our youngsters
- Calhanoglu - the same as for Draxler
- Hysaj - I'd rather keep faith in Dest and bring back Emerson
- Rui Silva - could be good as Neto replacement and competition for MATS but he'll surely go to a team where he'll start (rumours are he has already signed with Betis)
- Dmitrović - the same as for R. Silva but he has apparently signed with Sevilla
- Mandi - would be another 3rd/4th CB which we already have, don't see him as being a clear improvement over anyone we have. Also has signed with Villarreal according to rumours
Then in 2022:
- Mbappe - I'll mention him even if he doesn't fit that age criteria but he's the best player on this list. Don't think we'll ever have a chance to get him but if we could then do that (even if I'm not his biggest fan).
- Goretzka - would be great but Bayern will extend him before we'll have a chance to get him
- Pogba - nope
- Dybala - nope
- Kessie - wouldn't mind him
- Sabitzer - a very solid versatile player who I'd seriously consider for free. Probably won't be available though.
- Belotti - not sure about Italians at Barca but would be an improvement over what we have now.
- Gosens - would be a great competition and possible longterm replacement for Alba imo but rumours are he's off to EPL
- Zakaria - I've not watched him much but he was linked to likes of City. Like his profile but as said don't really know that much about him.
- Romagnoli - was linked to us a few times, don't know if he's who we should target though
- Onana - currently banned for a year, we have no idea in what state he'll be when he returns. And despite hate MATS is getting here he's not going anywhere so unlikely Onana would come here to be his backup.
- Christensen - was highly rated a few years ago but don't think he'd be a starter which we need (we have enough 3rd/4th CBs)
- Milenković - could be an option at CB but I've not watched him enough to failry judge him
- Edouard - I wouldn't mind gambling on him on a free next year but doubt Celtic will let his contract expire. Don't know if he'd be able to make a jump from Celtic to Barca and how much I'd be willing to pay for him this summer but there are quite a few strikers I'd look at before him.
So surely some interesting players who could improve the team but hardly see any of these players who we could realistically expect to sign having anywhere close to the same immediate impact as R10 or Eto'o did back in the days.