Gunners boss Arsene Wenger said on Tuesday that the deal was "almost done", according to Joe Moore of talkSPORT, and it certainly looks to be a good one for the London club.
Arsenal require a player who can function as a striker or a wide forward, and Sanchez, who starred at the 2014 World Cup for Chile, fits the bill.
The 25-year-old scored 19 Liga goals in a superb season for Barcelona and also provided 10 assists for his team-mates, per WhoScored.com, showing he can operate in either role.
His statistics are only bettered at the Catalan club by a certain Lionel Messi...and he's not for sale.
Last season the Gunners operated with just one recognised striker in Olivier Giroud, who made 36 Premier League starts in a 38-game season, per WhoScored, while injuries to Theo Walcott and Lukas Podolski also left the side without attacking reinforcements from the flanks.
Sanchez is the answer to Arsenal's problems, as Squawka's Daniel Anwar explains:
Sanchez scores and creates goals, is lightning quick, a sensational dribbler, and poses a constant threat to defences with his movement. Importantly, he can also play as a striker or on either flank as well.
The former River Plate forward proved at the World Cup that he can play in a central role—scoring two goals and providing one assist in four games, per FIFA.com—and thus can certainly take the burden off Giroud.
And maybe more importantly, Sanchez can play alongside the Frenchman and provide a supply line. The Chile international created 47 chances for Barcelona last season. Only Mesut Ozil and Santi Cazorla created more for the Gunners, per Squawka.
So while he can score, his versatility would not only allow Giroud to continue to operate as the main striker but would, or should, actually enhance his impact in matches.
Or as football scout Tor-Kristian Karlsen succinctly puts it:
Pace and flair were sorely missing from the Gunners as the early Premier League leaders tailed off last season—and Sanchez can provide both.
Having played at the Camp Nou for three years, the Liga winner should have no issues adapting to Arsenal's Barca-lite style.
In fact, he appears determined to do so after having his nose put out of joint by Barca's attempts to sign Luis Suarez from Liverpool, particularly as he was thrown in as a makeweight in the proposed deal, per David Kent of the Daily Mail.
He will be eager to prove a point, but just as importantly, he wants to play his football at the Emirates Stadium. He reportedly turned down offers from Juventus and Liverpool to do so, per Sky Sports.
That combination of desire and talent is a heady one.
If Sanchez does start next term in the red and white of Arsenal, they could finally sustain a title challenge in the future. And with a four-year deal mooted, it would be a lengthy challenge.
An attacking quartet of Ozil, Walcott, Cazorla and Sanchez would give the Gunners a strength in depth that has been missing for many a year.