Okay, that is a fair point. I have no idea whether sales of FCX are "flagging" and to characterize it as such was unfounded. What is clear from this announcement is that Apple is hoping to boost the sales of FCX, regardless of whether it's currently "flagging" or not. I still stand by the rest of my post, which is to say that this move makes Apple look like it is completely out-of-touch with the creative pro community. Whether sales are currently "flagging" per se doesn't affect the way that this announcement comes off.
I'm not aware of any specific publication that shows that creative professionals want an overhaul to the Mac Pro line, but every creative professional that I know (~15) has said something to that effect in the past year or two. It's not a citable source, it's just something that one picks up by paying attention to the chatter in the community.