Considering how well the game has sold on EA, maybe we might see some more companions added. I think 10 would be a good number.

If the 5 companions so far, I think only three are evil.

Lae’zel - Lawful Evil
Shadowheart - Chaotic Evil
Astarion - Neutral Evil
Wyll - Chaotic Neutral
Gale - Lawful Neutral

Minsc will be Chaotic Good, and the other two companions will likely be good too. I think this is a decent spread.