Facebook has definitely killed most forums. Like someone already said, most all other forums that were big at one time have diluted down to a handful of members. Sid really got ahead of the curve by hiring Steve and posting quality original articles. That has kept SVTP relevant to this day.
I think though FB has only killed local forums, which there really isnt a need for these days. You need your national forum that represents your make/model for knowledge, and your local FB page for organizing meets and such.