Don't know why you think the fanart cannot match the cat in the announce. First of all, the fanart isn't based on the announce. Also the cat in the announce is blurry, so it's hard to say something accurate about its tail or eyes. Also in the announce the cat is resized horizontally. It is because it came from Pokexperto? They also revealed the names of Pokémon Black and White before they were revealed officially.
If you don't want to believe, you are in your right. But remember one thing, if these statements are confirmed in two weeks as real:
"506: A small dog-like Pokemon. Probably a breed of the Shih Tzu race: http://bit.ly/djWCxl (but with brown-golden hair)."
"507: Longer dog-like Pokémon, has same face but with mustache. Face and legs are golden, body is dark grey. Also a Normal type."
"508: A dog-like Pokémon, resembles an adult Shih Tzu but with longer body. Long mustache and black-to-grey body http://bit.ly/9diX5S"
You won't call me desperate. =P
BTW, yeah, I think the starters evolutions are real, and don't resemble any existing Pokémon.