If we are still discussing the issue in July then Sony have a massive problem as they could be competing with a cut price 360 which could damp PS3 demand.
It is a 'problem' for Sony either way; better to have consoles on shelves when demand is high, and with some high profile releases this month... now would be a good time to have them here. Now if the new stuff arrives in a week's time, then the problem has been indicative of something good, with minor inconvenience. But July nothing - if PS3's aren't on the shelves by April, we are talking a major supply chain misstep. How do you think NPD March, April, May, and June would look without any new PS3 shipments? And if you are a gamer that decides to enter the present gen, and the only way to play is to get the 360, well, you're probably going to. That might theoretically be a customer where Sony is not even able to compete for them.
BUT, I do personally think we'll see the new revision soon enough. It is afterall what I am basing my own plans on.