If Juventus improve their performance in defense their chance for the Europa League title will increase quite much as well. I mean that they are really solid in defense as for the Serie A. However they couldn't show the same level of performance in their Champions League matches. Their defensive weaknesses sped up the process for them to be eliminated.
However if they manage to perform in the Europa League at the same level of their performance in the Serie A then I will add them among the favourites. But for now bookmakers are showing Arsenal as the closest team to the title. Arsenal have cared about not only the Premier League but also the Europa League so far. With this discipline level they really have a big chance to make it.
There is no doubt in my mind that Arsenal can play in the Europa League final... But the fact that Juventus will be that team, I'd be very doubtful... Sporting, Ajax, Man U, Barcelona in my opinion look much stronger... Although I have no doubt that Juventus will beat Nantes and qualify for the Europa League, I don't think they will win the title...
They are still in a team that really deserves to be considered, but the problem is there are other teams that are better than them. Arsenal are very clearly the biggest favorites to win this competition if they can still maintain the impressive performances they have shown so far. I expect other teams to be at the same level of seriousness in the Europa League this season, because usually they don't have much ambition to win titles here.