I think Vita will put up a good fight in the first year, trading blows with 3DS depending on game releases. But once Pokemon comes out, I think 3DS will pull ahead.
Sony will be losing money with every Vita sold WW so they wouldn't be able to drop the price, I honestly don't know how long Sony can continue to sell consoles at a loss, since it's a handheld it probably won't sell as many games as PS3 to make up the difference. Originally they said they wanted to sell Vita at a profit, but clearly the decision to drop the price screams to me "we are scared and can't compete with 3DS at a profitable price point".
you got a source on they are selling at a loss? it's the first time I've read that.