I thought I would start a post for speculation about how the series is going to end.
Here's my guess. We are going to see something akin to The Godfather ending -- with the kingpin antihero killing all the heads of the rival "Five Families" in one fell swoop, while at the same time personally confronting and killing the traitor on the inside of his "family." We will find out that all of this season has been part of Jax's master plan to turn all the other gangs against each other to weaken them. Then Jax will arrange the near-simultaneous murders of August Marks, Lin, Alvarez, whoever is now in charge of the One-Niners, and possibly others to consolidate his power. He will then confront Gemma and tell her that he knows that she was the one who betrayed him by killing his wife, at which point she will be killed too, or convinced to kill herself first. That puts Gemma in the "trusted traitor" role of Carlo from GF-I, or Fredo or Frank Pentangeli from GFII. ("I knew it was you Fredo! You broke my heart!"). Like the Godfather, the series will end by showing that Jax has become the king, but at the price of losing his soul and his family, which he claims he cares most about. His children will fear him, and will grow up wanting nothing to do with him (just like Michael Corleone). Success as leader of the club goes hand in hand with personal tragedy.