According to an ESPN report, Arsenal are already looking to offer Alexis Sanchez a new and improved contract, to make sure we don't even come remotely close to a Contract Saga™ with him. Alexis joined Arsenal only last summer, but already has made a massive impact, leading the team in goals last year and scoring a few that could end up on the list of all-time great Arsenal goals.
Alexis' current deal expires in 2018, so the matter is not yet urgent. But the goal is to keep the club's biggest names from entering the final two years of their deals without new ones signed, so Arsenal will attempt to get Alexis to the negotiating table before Christmas and get the issue sorted out as soon as possible. In fact, ESPN reports that Alexis could be made the highest-paid player at the club, which I think few could argue would be undeserved.
If successful, one expects that attempts to re-sign other big names would soon follow.