"
edit: In this very specific case, I noticed how there is "noone" in normal hc any more. I do want to level my chars there at the same time. But I think this will very soon stabilise once the initial hype of the new leagues is over (3-4 weeks maybe). Plus on onslaught a lot more people will die and might just return to their old hc chars within a couple of weeks because they don´t see themselves reaching the endgame there.
So I predict within 1.5-2 months there will be more (or at least the same amount of) players in the parent leagues.
I'm hoping that this is the case. One alternative to this that I can see is that people frustrated with Onslaught might not want to go back to standard HC and put the game down completely. They might be disappointed to come back to a ghost town.