My plan for summer 2022 would be investing as much as we can into rebuilding forward line as I believe with improved attack we should immediately be competitive in La Liga next season. With a better quality upfront we should be able to outscore most teams so probably still leaky defense wouldn't be that problematic. Not saying we'd win the league (if RM would sign Mbappe and possibly also Haaland they would be clear favorites) but we should at least be in until late into season not being without any options to win in November like last and this season.
It's pretty clear we shouldn't think about going far in Europe until at least 2024. Over next two seasons I'd expect us to qualify for Round of 16 and with a lucky draw maybe into quarterfinals and then not getting embarassed there like we're used to but regardless of how Laporta is talking Barca can't afford to have transitional seasons this rebuild was always supposed to take more than a year. It already started somewhat last season with likes of Pedri and Araujo (when not injured) establishing themselves in the XI but we're seriously in now after Messi left.
So if we can really afford to buy Ferran (in January) and Adeyemi next summer it would be a step in the right direction imo. Don't think we'll actually get both and I'd prefer Adeyemi between the two but Ferran is a clear improvement over what we currently have too. Don't think signing them both would be as impossible from a financial standpoint as it looks though. We should get 40m for Griezmann and probably 30m for Trincao. Either Wolves will use their option or Mendes will help to sell him to another EPL club for a similar price. If not I'd give him a chance but unlikely he'd get one if we'd buy two players who can play the same position and are a better fit for what Xavi wants. If only one of Ferran/Adeyemi is bought and Wolves won't use their buy option then keeping him as a squad player is a no-brainer imo as I think he's easily better than other kids we have.
If we'll further lower wages (which should be done with hopefully letting Dembele and Roberto go and God help us someone taking Cou and Umtiti) then (If I understand La Liga rules correctly) we could spend as much money as we'd sell players for on new signings.
Front three of Ansu-Adeyemi-Ferran would look very talented on paper but with obvious question marks due to their youth, inexperience and Fati's injury concerns. Also don't know how they'd fit together but I'd let Xavi figure that out (if he'd support signing both Adeyemi and Ferran then I think he'd do that with a certain idea how to use them), grow them together for two years and see where they'll get. If lucky we could find attacking trio for next 5-7 years, if not they're young enough to have a good (re)selling value.
I'd let Dembele go wherever he wants, clearly not worth all the troubles. Depending on offers would also sell one of Depay or Braithwaite. Despite his contract expiring in a year Memphis would bring us more money but at the same time he's also more useful to keep around as a squad player. If we don't get two starting quality forwards like Ferran and Adeyemi then keeping him is probably a must. Then IF Xavi would want a more natural #9 maybe that Cabral guy could be a solution for that role. Or someone of similar profile and price range. And to complete the bench pick the best out of the Moroccan kids (Ilias, Abde) or the Demir brothers. Loan/sell with a buy-back those who won't make it.
As for midfield I think we're pretty set there for next 18 months. Would obviously like to see Busi replaced but don't see it happening. Let's just hope Xavi and/or Laporta won't even think about extending his contract beyond 2023 and that Xavi will at least try midfield formations without him when we get back Pedri. Signing someone like Boubacar Kamara on a free would still be a smart move though. He could potentially also cover as a CB (although hasn't played there much AFAIK).
In defense I'd really like to see Pique retiring/go to MLS and get Azpilicueta to bring a true veteran presence and leadership we've lacked for years into backline. Hopefully Araujo can finally stay fit and we could see how he and Garcia will look together in a 4-man defense. Offload Umtiiti at all costs and see what we can get for Lenglet. Wouldn't undersell him as he can still be good as a 3rd CB (and he's a leftie we don't have) and AFAIK after his contract renewal he's still on a relatively low wages until 2023 but if an offer of 25m+ he should be sold.
As for LB we're stuck with Alba like it or not. Doesn't look like Xavi think Balde is ready for first team minutes so far but we'll see more about that in coming weeks/months. If Gaya won't renew with Valencia he'll have just a year left on his contract and we could potentially get him for relatively cheap I would do it and loan Balde to get La Liga experience. Don't know what to do at RB if Xavi really doesn't like Dest and he'll be sold. Don't think a 40 year old Alves is an answer and neither are Roberto or Mingueza. I think we could go through one season with Azpi as a starter and Oscar as backup but would then clearly need to address the position in 2023 alongside possibly signing another CB if Araujo-Garcia won't work out well.
So for 2022/23 season I think something like this could be doable and would be an improvement over what we have now. And improving a team season by season is what we should aim for as we clearly can't fix all the issues in one year.
GK: MATS, Onana (or more likely Pena)
defenders: Azpi, Oscar, Araujo, Garcia, Lenglet, Kamara?, Alba, Gaya(?)/Balde
midfielders: Busi, Frenkie, Pedri, Gavi, Nico, Kamara?
forwards: Ansu, Ferran, Adeyemi, Memphis, Cabral, Abde/Ilias
tl;dr: Keep mostly status quo (besides maybe signing on a cheap/free) in midfield for next 18 months and let youngster develop under Xavi's guidance, invest big (how much we can afford) and reload offense in 2022 and then it's a turn on defense (and possibly) GK position in 2023.
Also important, have patience with youngsters while they're going through growing pains.