YouTube is now again calling these "friend invitations" (at least on the message subject headings). Perhaps this is a step in the right direction, back to restoring friends on YouTube.
But when you click on one of these "friend invitations," the message refers to the user as a potential "contact." And if you look at the folder column on the left, they still refer to this folder as "contact suggestions."
YouTube said they were trying to reduce confusion by eliminating friends, but all they've done is create new confusion every step of the way.