I don't see a resemblance at all o.O
This is true although there is a butterfly species with sylvia or something like that in it's name and Silver Wind is a bug move. I'd say bug is highly unlikely but plausible.
Tropius is a flying type, that throws that out the window. Further than that Gyarados, Mantike, Doduo and Dodrio don't have wings and cannot fly (well... Doduo and Dodrio can learn the move but are flightless birds) which could very well mean Sylveon will be flying type, as much as that seems unlikely looking at it's design.
4. A new type at this stage of the series is highly unlikely. The reason Game Freak introduced the Steel and Dark types was to balance out the Psychic and Ghost types. Introducing a new type this late in the series would require adding several new Pokemon with that typing, creating new moves specific to that typing, and creating Pokemon who are immune to or resistant to that typing. I am of the opinion - which I hold with a degree of confidence - that no new typing will be introduced.[/QUOTE]
I am in full agreement with this.
Overall Sylveon LOOKS like it will probably be a Normal-typed eeveelution but I'd say that flying, bug and even ghost (I get this from its eyes and its weight) could be possibilities. I'd say it is most likely either Normal or Ghost.