In week 15, Luton will face Arsenal tonight, and in my opinion this will be an easy match for Arsenal to get 3 points even though they will play at Luton's home ground and will continue their victory.
However, after the match against Luton Arsenal have quite a tough schedule towards the end of the year. And they will face Aston Villa and Liverpool, two of the top four teams, as well as Brighton and West Ham United throughout December.
You are correct that Arsenal will have an easy way winning that match. Although Luton Town was promoted to the Premier League, they are still playing very poorly, and I don't think they can avoid dropping back to the relegation zone with their current performances. Arsenal will undoubtedly win this match in order to secure their place at top of the league. However, they will face tough opponents in December, including Brighton, West Ham, Liverpool, and Aston Villa. I find it hard to think that Arsenal will be able to defeat the four clubs given that they still have one Champions league game left to play. They can win like two out their next four premier league matches.
Anything can happen in a football match, but Luton town against Arsenal, there's no doubt that Luton can compete with them, especially at home. Arsenal will still find it easy to win the match.
From any point of view, it is clear that we can predict who will win this match. Luton Town's only advantage is that they play at home in this match, other than that there is nothing to be favored from them.
Arsenal must be able to make the most of this match, not necessarily scoring many goals, but they must win 3 points, regardless of how many goals they can score. They must also be prepared, because Luton Town will most likely play with a defensive strategy. They might just rely on counter-attacks once in a while and capitalize on Arsenal's mistakes.