The current rumor is that GBS is being shaped up to be sold off.
The growth units are starting to take shape and earn revenue, but those figures aren't being earned in GBS.
Additionally, a lot of the GBS work is now being done by the respective business units.
For example, IBM Cloud is sending in teams to do the business analysis and even helping out with the roll out of the new products (aka delivery).
In other words, GBS isn't the only business unit doing the "services" part any more and there is no need for them.
Also the fact that Bridget Van Kralingen has been replaced with somebody from Accenture is a telling sign of what is about to happen.