The Premier League will most likely get 1 additional spot for the Champions League next season, depending on the achievements of the English clubs in all European competitions this season.
So the 5th position in the league shall join in the Champions League and the 6th position in the Europa League.
Manutd still has a big chance to take part in European competitions, because England has 5 clubs competing in all European competitions now.
With the new format, it will indeed be very possible if the EPL team does that it's just that for now I see is what if in the end there are new format rules when adding Champions League slots but this season Liverpool who are in competition in the EPL for the championship race (systematically in the top 4) and they become champions in the Europa Legaue because they are now competing in the quarter-finals and the big chance of winning is still very much there for now.
When the automatic slot for the Europa League champion (if Liverpool wins) whether there will indeed be additions from other clubs or not because in the end we can see it even become 6 slots if the new rules are 5 EPL clusters in the Champions League as well as the Europa League champion who is automatically included in the Champions League the following season.
Is this also possible or are only 5 slots still used?
Because if it is only 5 slots, I think all leagues are still possible, especially for last season we saw in La Liga who got 5 slots and the previous 2 seasons there were clubs from the Bundesliga who got it.