I posted this on G+, but figured I would post it here too.
As a user of RHEL and CentOS, I use each for specific purposes. Several of the purposes I use CentOS for, Redhat wants me to use RHEL for. Now they could easily make CentOS less of an acceptable option almost forcing me to use RHEL since I use RH as my standard infrastructure distribution.
CentOS has always taken revenue away from RH where a full blown license of RH wasn't necessary and RH knows this. I have no doubts this move is to strengthen RH position and profitability. From what I read in the FAQ about this joining, Redhat requires that Redhat Employees have a controlling share of the CentOS board.
In the end, we will just have to see exactly how Redhat intends to steer CentOS.