I don't consider Sevilla winning Europa league next season but it is possible if they are in form because we all know that they have the experience more than most of the countries playing in this league next season.
On the other hand, it is not possible if they are not in a good form because it is only string clubs that wins trophy and there are a lot of clubs that will be aiming at lifting the trophy and for that reason no club should be underestimated. I hope to see more surprises next season just a sit wad last season.
Next season it is still very possible to expect more surprises in the Europa League because besides there are many big teams who will compete there, of course there are many other teams who are not favorites to win the title but those teams can beat big teams like what happened last season when Liverpool lost in the Europa League. And usually teams like Sevilla or others who are not too focused on the domestic league will put their focus more on the Europa League for a trophy, but as you said in the Europa League next season nothing is easy to achieve for any team except for the team that really has great ability.