De seating or de notifying is not the complete solution as here PTI suffers too as they have now 25 less members in Punjab Assembly, the opposition loosing the edge of 25 MPA's who crossed floor is fine and justice is served here....but only partly.
Ideally with them de seated, new by elections need to held ASAP in these 25 constituencies, so that PTI gets the needed 25 seats for the confidence votes for CM post.
And in future there will still be floor crossing even if there votes are not counted, but they can be bought to not vote for their own party so as to create problem for the affiliated party( a case of a failure of someone deemed as success for the other)