So far we have two confirmed companions, the Dog and Codsworth. I've always thought of the Fallout 3 and New Vegas companions as fitting the same kind of mould and so far Fallout 4 seems to head in the same direction:
The robot:
FO3: Sergeant RL-3
FNV: ED-E
FO4: Codsworth
The dog:
FO3: Dogmeat
FNV: Rex
FO4: Dog(meat?)
The professional tough guy:
FO3: Jericho
FNV: Craig Boone
The not-so-tough guy:
FO3: Butch DeLoria
FNV: Arcade Gannon
The tough chick:
FO3: Clover
FNV: Rose of Sharon Cassidy
The ghoul:
FO3: Charon
FNV: Raul Tejada
The BoS:
FO3: Star Paladin Cross
FNV: Scribe Veronica Santangelo
The super mutant:
FO3: Fawkes
FNV: Lily Bowen
I expect the other roles to fill up in addition to the dog and robot. A lot of people are very fond of ghouls and super mutants so I definitely expect one of each. Same goes for the Brotherhood of Steel, especially since they have a rather prominent role in the gameplay demo. A well-armed 'tough guy' has been in every Fallout to date (Tycho, Cassidy, Jericho, Boone) so that will most likely happen as well. I also expect an android companion, perhaps this game's version of Butch/Arcade, Boone/Jericho or Clover/Cass. And lastly I hope/expect your spouse will eventually become available as a companion.
What do you think? Any expectations, hopes or dreams? Do you think we will be getting eight companions like in FO3 and FNV, or do you expect more/fewer?