I really cant tell anything from the way they look right now. I mean, look at every other starter pokemon in existence. It's so hard to tell from that base form what they'll be come later on. I mean, in retrospect, we can look back and go (ooh, now we can see it going to this) but it's too hard with no information. I can't tell diddly with Froakie, Chespin, or Fennekin. Just about nobody saw Oshawott go from a bipedal seal to a quadrapedal Sea Lion.
With that in mind, all I can do is say what I hope each ends up becoming. Once the 2nd form comes out, then I can probably make a good guess as to the direction a form will go. But for now, here's my hope as to how it'll end up:
Chespin- Grass/Dark (Bipedal hero look to him with a leafy cape and spike/club tail; dark markings around the eyes like a raccoon)
Fennekin- Fire/Electric (Sleek, thin & elongated Fox with electric yellow highlights or a fiber-optic cable look to its sides and and fire/sparks from the fluff of its ears)
Froakie- Water/Steel (Armored Frog Knight; I'm essentially picturing Frog from Chrono Trigger lol)
I know the typings aren't likely (since Grass loses its advantage over Water and Fire gets the advantage while Grass gets screwed) but I'd like to see it anyway