This is bordering on complacency. What you have posted is correct - but it describes what happened when we had no key injuries. We are an injury to DCL and Tarkowski or Branthwaite away from grave peril. If we lose DCL again - which sensible people would bet on - then our advantage over the promoted clubs shrinks. Throw in only one of them going on an unexpected run, and the alarm bells will ring loud - because realistically it's any three from four now (us and the promoted clubs).
Another point to remember: we go to Burnley in December. If we don't win at Turf Moor, we will have played all three promoted clubs in the league this season - and failed to win any of those matches. There's going to be an awful lot riding on that match, especially as there might not be too many points for us over the upcoming run of United, Forest, Newcastle, and Chelsea.
We may not get relegated - but there are plausible paths to relegation for us and we have a huge fight on our hands now against three squads who have just been given a precious lifeline and route to possible survival. Complacency is our biggest enemy.