I do not see Aston Villa going down from the top-four position in a few weeks, Aston Villa will be in the top-four position for a very long term. Aston Villa's coming from behind to beat Brighton shows that they are fully ready to win the Premier League this season.
I understand why you are so confident in saying Aston Villa will be in the top 4 for a long time because I saw their match schedule and there are no big matches until next March there are only a few games against Manchester United and I'm not sure if they can be called big games because in fact Aston Villa's performance is much better, but next April they will face 2 strong teams such as Manchester City and Arsenal well, here we can't be sure whether Aston Villa is still safe or vice versa. As we can see in the table, each team has adjacent points meaning there is still a chance to overtake each other among the top 4 but to win the League I'm not sure Aston Villa can do it.
Aston Villa has beaten Manchester City and Arsenal before, and Aston Villa can beat Manchester City and Arsenal again for the second time. You are saying that Aston Villa can not win the Premier League because they are not a big club, but never forget when Leicester won the Premier League, nobody believed they would win the Premier League trophy that season.
Aston Villa is an important team and I think their biggest chance is Unai Emery. He is a very experienced coach and one of the coaches who knows best what to do where and how to play which players. They are currently pushing for the top of the league with this squad and they are also in this race. Aston Villa is a team with a championship possibility and if they make it to the end of the league, they can even become champions. I think we should not be unfair to them.