To me, announcing the Worlds team after 4CC doesn't really make a whole lot of sense, other than perhaps for the ladies if it should come down to a Leung/Phaneuf duel, or should some toher lady surprisingly step up... (but frankly, I tend to think that if Phaneuf cannot beat Leung outright at this stage, then send Leung!)
Making the assumption that ALL of the top skaters will get to go to 4CC - and i don't see how SC could refuse any of the medalists (and therefore leading Olympic team contenders) the chance to compete at such a major event held at home and at the future olympic venue... and so, in the case of the Men, for example, there would be nobody to compete for the "last spot". In pairs, it could potentially be a test skate for L/A, I suppose, which would be arguably justifiable - but will they be recovered by then? (and if they go, do they then get turned down for worlds if they don't attain a specific score, sending our bronze medal team to Worlds without any significant international experience?). And in Dance, it seems highly improbable that team #3 would be consdered to be in a skate-off with Crone/Poirier...
It also seems highly unlikely to me (though what do I know?!) that any of the top skaters would want to turn down the event for more training time, thereby opening up opportunities for others to compete for spots on the team
I'm pretty sure that in reality, the team will be unofficially "decided" after Nationals