Why would KHL stretch into May?
To have more than 52 games in regular season? Look, you need 60 days for play-off, that can not be changed if you dont want to play best of 5 series. So, league need to finish regulars in early March to be able to finish play offs until WC in May. Right? But, KHL does not like this model, KHL needs more games in regulars than 52. KHL does not have 12-16 teams as euro leagues, but 28 and will have 30. Solution is to move WH Championship to February/August etc (which IIHF would not like to do, right?) or to play Gagarin Cup play offs during WH Championship in May (what is not problem for KHL).
If you follow KHL for a year or two, you must know it. KHL wants more games in regulars. Only Q is how to achieve it.
You can claim that WH Championship is popular in Russia, Russians love it and want to have their best squad, so no chance KHL to stop the best players from WH Championship. That is true, but this is FHR´s job, not KHL´s. You know, there is an battle among them within russian hockey. Just remember how KHL was created.. long story.
Btw, what will euro federations (especially Finns) and IIHF say if this scenario comes true? No NHLers, no KHLers... why to held WH Championship?
KHL leadership is not naive as many ppl would like to think. These guys dont give up.