fangraphs projects them at 85 wins. They are likely to pick up another OF (Cain maybe?), so they are still a competitive team in 2018. But their window is probably closed after that for a while.
I think FanGraphs is over-valuing the Giants roster, especially if the DBacks succeed in retaining Martinez. Even if Melancon comes back at his 2016 form, their bullpen is a big weakness. I don’t expect them to repeat their 11-8 season against the Dodgers with their current roster, or even with a plus-offensive OF added, and overall the NL West is going to be tough again.