My thoughts

According to the LOTG today, it probably isn't handling. You can't call it deliberate, and there's no other official application that says it's handling. FIFA/IFAB have previously indicated they don't want to see goals scored directly with the hand/arm, but this wasn't and technically the LOTG haven't been modified to make that explicit (yet). Came off the forearm, then hit the hip, then went in. The arm was close to the body and not raised up. I think if you see that ball hit the forearm and go straight into goal yesterday, they wave it off. The ESPN guys were ranting about how he gained an 'advantage' from it, but that is NOT in the LOTG right now.

However, next year: it's handling. The handling laws are changing and it's all for the better. Key portion:
•Deliberate handball remains an offence
•The following ‘handball’ situations, even if accidental, will be a free kick:
•the ball goes into the goal after touching an attacking player’s hand/arm
•a player gains control/possession of the ball after it has touches their hand/arm and then scores, or creates a goal-scoring opportunity
•the ball touches a player’s hand/arm which has made their body unnaturally bigger
•the ball touches a player’s hand/arm when it is above their shoulder (unless the player has deliberately played the ball which then touches their hand/arm)

From the explanations, you can see the intent:
•football does not accept a goal being scored by a hand/arm (even if accidental)
•football expects a player to be penalised for handball if they gain possession/control of the ball from their hand/arm and gain a major advantage e.g. score or create a goal-scoring opportunity