The Special One is the only one Chelsea needs.
IMO, Chelsea needs more than just him if you think you're going to win the title. You need another striker for starters.
Falc could come Lukaku could come back from loan, Piazon should come back from loan. We will buy a central midfielder and defender. We may spend a lot, we may not but we had a lot out on loan and as it stands now with the crap storm of a season we had we have the 2nd best GD of the whole league, while setting a record for games played in a campaign.
I think the Schurrle deal is pretty much done (unless Jose vetos) and that will help to give us a variety of options going forward. If we do bring in a striker, I am hoping for Lewa or Cavani over Falcao (we need too much help in CM/CB to splash that much cash on Falcao). Sending Kevin de Bruyne on loan to Dortmund to lessen the Lewa fee makes sense. Lukaku is probably ready to come back, but if we get one of the big strikers I can see him spending another year at West Brom. Piazon isn't ready for Chelsea's first team yet and I would rather see him stay on loan than play 2nd team minutes at CFC. Essien coming back will help with depth in CM, but another top quality player is needed.
This is how I see the summer shaping up for CFC:
IN: JOSE!, Schurrle, Lazar Markovic (go straight to loan), Essien (from loan), Elite Striker, Starting caliber CM (Moutinho/Alonso?), CB to pair w/ DL, Backup GK
OUT: Marin (loan), Benayoun (free), Malouda (free), Ferreira (free), Turnbull (free), Hilario (free)
???: Lampard