Has Infinity Ward left Activision?

Today Activision announced that a developer named Sledgehammer Games will be starting a new Call of Duty franchise. It's reported that the new franchise will be an action aventure game; a first in the franchise. In other news coming from Activision, Vince Zampella and Jason West ( Both head of Infinity Ward.) have left the company. There is no report on why this happened, but there is a rumor that it could be because of a new IP that they were working on. Finally in relation to Infinity Ward. Activision has asked IW to make a Modern Warfare 3, but the company is relunctant to do so. Does this mean that the well know and one of the best selling series be on it's way out as well and onto a new publisher? Let the rumors begin.