Those are four separate questions, and I would dispute all but the first.  I believe you if you say your sales are down so far.  Mine aren't; in fact at this moment I'm on track for a record month.  It could still tank, especially with a holiday weekend coming up in the US.  But I'm doing very well at SS this month and I doubt I'm in the minority.

And even if lots of people are down, is it all because of DPC?  Maybe but I doubt it.  As the old saying goes, "The plural of anecdote is not data."  That a few clients may decide to sample DPC is bad, but it's not enough to make me panic over the whole market.  Especially when a lot of suppliers have either pulled their content or won't put up any more.  Fotolia is also at risk here; if DPC costs them new and valuable content at both their sites, they may have hastened their collapse.  I can only hope.

There's another saying that's relevant here: "Post hoc ergo propter hoc."  That means "After, therefore because of."  Sometimes it's true, but it's often not.  The establishment of DPC may precede a decrease in sales for some suppliers to some other sites, but that doesn't mean that it's the cause of that decrease.  We look for patterns, and we often see them when they aren't there because we expect and want the Universe to behave in an orderly fashion.  That's why people see the face of Jesus in toast.  It's not a miracle; it's just a belief system gone haywire.