I think even if Manchester United want to copy Chelsea’s process of reviving their squad it will be really difficult because of United’s financial situation currently. For United to be able to make notable changes they will first need to overhaul their squad, giving way for incomings before they can make any significant changes and I think that is the stumbling block holding them from making signings currently.
Let's forget about the financial situation faced by Manchester United. Let's assume Manchester United successfully signed the players they want after letting go of their old players. Can they stay up to a season or two without having a good performance? I am asking this because it took Chelsea more than a season before their performance began to improve the way it is currently after changing coaches.
Manchester United is no doubt in need of a new set of players for the progress of the team. All that will take time before the players begin to know each other's playing patterns.