Arsenal are definitely going to win the premier league this season. I think they already have the team to compete for the premier league, but just need a few pieces of the puzzle(A world class striker and a left winger)to win the premier league . If they can complete the signing of Sporting Lisbon striker Viktor Gyokeres and probably Rodrigo from Real Madrid, then they are good to go all the way to win the league.
With the commitment I am seeing from the management in getting the players, it shows they are serious about winning it.
But after all this signing and they still fail to win the premier league,  then we can all conclude that Arsenal is not ready and will not win the league for a long time.