I don't know about other players in the community, but for me the competition comes from wanting to play against others, and win. The end goal is winning, and I feel that there are many who would agree. That's why so many of us play and will continue to do so. As long as another league has the players to play against I don't see why there would be a lack of competition. It might be weaker on the top end at first, as some old timers will refute change and decide to not take it seriously. However it's only as competitive as you make it.
That said, i'm only willing to move to another league if many other players do as well. I'd rather be able to play the game I love against others (even if I have to have paid for malware), than to not play at all.