As a non-champion and weak club coefficient, it will be very difficult for PSV to get into the Champion League.
Should Ajax be eliminated after yesterday (you have to miss so many penalties, even if PSV also missed two), Ajax will have failed to finish the season on a positive note and will have to see that they don't lose their Europa League place against AZ at the weekend.
i am not completely sure how the draw works eventually when it comes to the Champions League qualification round, but last year they started in the third round and eliminated AS Monaco, which isn't that bad. In the final round they were up against the Glasgow Rangers, but even then there aren't really many weak teams anyway. You can get a team like Benfica against you if you have to go through the Champions League qualification phase. Those teams who make it through that path actually can't be that weak anyway. It comes down to whether you are lucky in the draw or not.