My random thoughts:
I think it's a bit of an open secret in the media that this is probably untrue, but there's nothing wrong with reporting its existence or the fact that Buzzfeed published it. Trump really fell into a trap when he reacted, confirmed that he was briefed on it, and mentioned the intelligence agencies.
He should have called it fake and moved on. The story would've been overshadowed by the million other things happening today.
This story is going to have staying power, unless the "4chan sockpuppet troll" comes forward -- which would put his life in jeopardy now that Putin's integrity is involved. I bet he regrets alt-right trolling now.
Buzzfeed pulled a really risky gambit, but I think it paid off. They successfully baited Trump and deflected a lot of the blame from themselves by getting CNN roped into it. If it was just them on the battlefield they would've been Gawker'd.
I find it amusing to see the alt-right and 4chan desperately trying to prove this is false. People are conditioned to ignore them on social media, and the 4chan screenshots of people gloating about trolling aren't helping their case. It's really a boy who cried wolf situation.
And finally, although I believe fake news is a both a right wing and left wing problem, it's no secret that the right wing has been particularly receptive towards it. I think they really took the left wing's integrity for granted. Today they learned what would happen if the left wing decided to stoop to their level. (not saying that it happened with pissgate, but the message is clear)