It's even shorter: 4 days before you cannot update your staging server if you have one. The people who forwarded me this announcement were really surprised about that (they use sandboxes as staging server).
Those people were not concerned about the speed at which to convert, more about the sudden extra cash needed.
(note that I don't blame DotCloud for this really! Just giving a data point on something I heard).
I don't disagree with Dotcloud's decision! But our entire stack literally depends on them, so here is another data point about how this will affect us.