Well that will be a great haul. Personally don't like the idea of Busquet. Not because he is not great, but I hate when coaches take a player from an old team to try to recreate what they achieved together.It would likely be more...
------------ Busquets ------------
-- Gundogan --- Fernandinho -
De Bruyne ----------------- Silva
------------- Aguero -------------
With the front three playing very dynamically, interchanging positions as needed, while Gundogan and Fernandinho alternate late supporting runs and Busquets rarely moves past the middle-third but is always available for the "reset" pass. Sterling can replace Silva if pace and directness is needed and Busquets can be dropped for Nasri further forward against lesser opposition or if we are chasing it.
I think it would actually make us very solid, with a lot of creativity and energy, depending if we can get in the right fullbacks to complement our fluid forward system.
My dream summer transfer window would actually be Busquets, Gundogan (healthy), Griezmann, Fabinho, Wendell, and Oliver Torres.
But we will probably only get one of those.
I'd rather new players to work with and create something new. Same reason I'm not so big on getting Thiago either. If it's a bit role player who the manager thinks his ready to explode (I.E what Thiago was when he moved to Bayern, then great.
But established superstars from your old squad seems like going back to me.
I'll take your Fabihno,, Gundogan and Griezmann then add Pogba, Hector, and Laporte.
I think that should cover every position nicely.