Galaxy S4 Nexus

After seeing this and a great deal of other things like it, it got me thinking.

Is the "Nexus" S4 going to influence sales of the normal S4?

Is this a sign that Google is friends with Samsung or is it a show of "taking back" Android?

And is it actually worth the buy when I can root an S4 and put CM10.1 (or what have you) on it rather easily?