I'm sure Liverpool will find a replacement for Firmino and not sure Mbappe will move to Liverpool even though Liverpool have quite a lot of money, because it seems Mbappe is more interested in Madrid than Liverpool and playing in the EPL, talking nonsense seems to never end that's why a lot of media who continues to force things that are difficult to discuss like this. after all Liverpool will not be able to buy Mbappe from PSG.
I'm sure PSG charge high or expensive fees so it's difficult for Liverpool to bring him to Anfield, but even so the club that makes the most sense is madrid and I'm sure Mbappe even though he will move from the PSG club he will play in madrid more than in any other league including Liverpool EPL.
Liverpool already have players who can play in the number 9 position in firmino’s absence. Darwin Nunez and Cody Gakpo are both capable of playing in that position while Dias and Jota play on the left flank, there is no problem of getting a replacement for Firmino except Jurgen Klopp decides he needs an extra pair of legs to boost the depth of the squad but outside that I think Liverpool need to bring one or two defenders in this summer and they are good to go.
City could not keep Gundogan in the team, this is perhaps a very significant loss for Guardiola, even a salary increase did not help, but Gundogan was more interested in the duration of the contract and Barca offered him a contract for two years. It's hard to say how significant Gundogan's absence will be for City, but he was without a doubt one of the most important players in Guardiola's scheme. But there are no irreplaceable people, so Guariliola will find a replacement for Gundogan.
This is certainly a loss for Manchester City but that shouldn’t be a problem for them in the coming season because City are already surplus of midfielders, Guardiola already have replacements on standby to carry on at his departure. Kovasic has also joined this summer. I am very confident that Gundogan’s absence will not upset the balance of the team.