Manchester city and other's aren't so much of a reason we would think we have to wait till they are performing poorly before Liverpool gets a chance, at this point they have all gotten equal chances and if Liverpool maintains a consistent good form, they can even stay ahead of Manchester city already.
Manchester City have enough strength to defend their title and continue their domination in Premier League. Other clubs will try to challenge and take over the league title from Manchester City. Two biggest competitors are Arsenal and Liverpool but Arsenal look to be more promising than Liverpool.
We may not see any big changes in the league even in the next season. The teams that dominated the top of the table could still be the same and the fight for the league title will possibly be amongst Manchester City and Arsenal as usual. The competition is a fierce one and it is always a fight of the survival between this top teams in the league. Manchester City could be replaced and defeated from not winning the league title, but that team has to show their more prowess to make that happen. Arsenal have tried for two seasons and have failed to make that happen and they are still the best team in the league to make that happen even in the coming season. If Arsenal can make that happen next season, that will be the greatest achievement for Arteta and Arsenal in a long while now ever since the days of Arsene Wenger.