Apart from Manchester City, other major teams have performed really badly in the last Premier League season. In the next season, those teams will want to build themselves up so that they can correct their mistakes and perform as well as Manchester City.
I don't agree with your assumptions, I think Arsenal and Manchester United had good performances last season, but they can't compete with teams who have a high level of consistency like Manchester City. Arsenal failed to maintain consistency due to the pressure exerted by Manchester City, but that's only normal because Manchester City is the better team.
Next season will be different mainly because these teams have built more quality from squad depth, but I think Manchester City are big favorites to secure the title. Arsenal, Manchester United, Liverpool, Chelsea and Newcastle have all the chances to end Manchester City's dominance, but the chances won't be any bigger than what Manchester City have so far.