I was wondering the same thing. I kept waiting and waiting during the entire episode expecting for something to happen that would bring Brian back but it never happened. The fact that it was a touching episode maye make me thing this may be the real deal. But the way Family Guys works, anything is open. They will probably try out the new dog looking for the audience's reaction. I think he will be back if ppl don't like Vinny. I personally not a big fan of him so far.
As someone who lost his dog 1 month ago to cancer (he was only 4) this episode touched me deeply :(
I remeber when my aunt's dog "Freeway"; a huskie died when I was a little kid; I used to visit him everyday, basically it was my dog but my mom wouldn't allow us to take it...he died so horribly; he lost his sight, then hearing, then hair, then it died. Their were days where I would just sit with him and pet him for hours as he was to sick/weak to move until the day I went to visit him and my aunt told me he died overnight....I cried hard that day :(