Sanda is also known as "practical Wushu" so if you were to identify it with something, it's NHB Wushu.
SanDa is basically boxing, Wushu, Shui Jiao and Chin-na strung together. There is however, little emphasis on Chin-na in competion but Shui Jiao is one of the main tools of San Da.
The throws in Sanda are similar, if not, exactly like the ones in wrestling[Greco-roman] with a little more emphasis throwing after catching a kick or parrying.
Can we call it Kung Fu? Yes. It requires kung-fu, but it's not an internal styles, it's an external like Wing Chun. The blocking and parrying are similar to Wing Chun, the elbow techniques are mostly derived from Baji quan, while punch/kicks are from many arts.
It's mainland China's version of MMA without external influence.
It is indeed a style. But saying it's kickboxing is kind of wrong in my view, it should be categorized into an MMA style. Look at Cung Lee, he's doing fine.
Sanda is an art. Sanshou is a type of competition.