Seeing Aston Villa unable to maintain their position in the top four is very possible because their current position is quite helped by Tottenham experiencing a decline due to their players being injured, but I think Arsenal will stay in the top four and if they fail Arteta's position may be threatened, and Tottenham to be in the top four is very possible but West Ham doesn't seem like it, they can sometimes appear surprising but also disappointing afterwards.
Aston Villa only suddenly rise in this season and join top four and it will be very challenging for them to maintain good performances and defend their position in top four. Arsenal, Tottenham are two biggest competitors with Aston Villa with current table because Aston Villa have only 3 points more than Arsenal and Tottenham. They have same total matches like Tottenham but already played one match more than Arsenal. This means if Arsenal win their match, they will have same total points as Aston Villa.
Other clubs behind those three clubs will have many works to do to reach to these three clubs and I honestly don't consider they are big threats for Aston Villa.