If United have a slow start they won't get top four. Your start reads like a championship schedule. You have to pick up points from those games.
If United have a slow start (probably because the team struggle to grasp Louis van Gaal's methods) they will fall behind.
But why stop there?
If Chelsea don't perform better against the weaker sides, if they don't break them down better yet fail to perform ridiculously well in the big games, those dropped two points here and there will see them fall behind.
If City don't perform better away from home yet don't replicate their incredible home performances of last season, those dropped points here and there will see them fall behind.
If Arsenal don't sustain their good performances for the duration of the season, that drop in form could cause them to fall behind.
If Liverpool don't match their form of last season, if they don't react to the fact teams will treat them differently, if their many new players don't immediately gel, if their intensity cannot be sustained from a mid-week champions league game to the weekend premier league, if they do not cope without Suarez' magic, if Rodgers' attempt to create a world class team from not so world class players doesn't work this coming season, if he gets it even slightly wrong the opponents will punish them and those dropped points here and there will see them fall behind.
It's not just United fans that must worry this coming season. Even Chelsea and City have areas they must improve, and along with Liverpool and Arsenal, nobody is safe.
I for one am very grateful for the lack of champions league football, we will benefit immensely from the extra time on the training ground thus increasing our chances to grasp Louis' ideas and implement his instructions to the letter.