Newcastle are definitely the favorites to clinch that advantage of having the 5th position which automatically grants them champions league football.
Like you likely said, they are playing better towards the end of the season also coupled with the fact that they have an extra morale boost from the trophy deadlock they just broke, more team morale
Their opponents would have been a stumbling block but Arsenal wll be more focused on champions league, man united doesn’t really have anything to play for just trying to understand themselves as a team so i only see Chelsea as a threat. Lets not forget they do have a game at hand
For me I think Newcastle are playing with the happiness of winning a trophy this season, ever since they won that trophy their performance has been wonderful and they are just flexible, their runs and marking has been great but I feel it will expire soon because we all know Newcastle how they are not as serious as they can be, playing a draw losing games they are suppose to win and now they display something different and I'm still not trusting this new style of winning and performing well every week. For Arsenal I don't think they'll be dropping any game because of Champions League, every game for them is important but the problem is how serious are they going to take each game both the EPL game and the CL game? Is just a mattee of time to see how good they can manage the remaining games.