Hm, well, I guess I kinda view the final evolved-starter types like so:
Fennekin, I guess I agree that it looks like it might be a Psychic / Fire final evo, or it could be just a pure Fire type. I...also have a hope that it can be Fire / Electric type too,which was me looking at solely it's colored body(?) Just saying, it can possibly pull off as an electric type too.
Chespin, it sort of reminds me of a platypus, so maybe it can be, say, Grass / Water? Although, GF has never made a starter that has the same type as it's brother types (like Grass + Water in this case) so, I guess that's sorta unlikely. Chespin's reptile-like tail sorta intrigues me too, which maybe it's final evo could be either part Dragon, Dark, or Ground?
Froakie, well, yeah, it can be interesting that it's final evo can be part Flying. I think that's what I'm betting on too!