So, the Writers Guild of America is continuing negotiations, trying to come to an agreement over a new contract. The contract is with the Alliance of Motion Picture and Television Producers, and they represent TV networks and movie studios. The Writers Guild is planning to go on strike (again, remember back in 2007 when TV shows and movies were delayed/reruns?).
This could mean Game of Thrones being delayed, among many other shows returning to TV this year. The strike in 2007 lasted 100 days, and that put a ton of production extremely behind schedule.
The reason for the strike is that there are so many different shows on TV. You might think that means more work for writers, and it technically does sometimes, but they’re payed per-episode, not per series. So with so many series-es (what’s the proper way to say that?) on TV this year, they’re running fewer episodes, which means less pay for the writers. They’re fighting for a better pay structure, and threatening to strike again if they can’t come to an agreement.
Some more details available here.