What that IP will turn out to be remains to be seen, but apparently, Microsoft "is keen to leverage its huge back catalog" acquired alongside the Blizzard studio. The fact that this team will supposedly work in a double-A capacity perhaps suggests that it will build smaller projects over at Microsoft HQ.
To that end, we're also not sure about platforms here. The report claims that a bunch of King developers — the third pillar of ABK that makes Candy Crush — have been pulled over to this studio, with mobile the potential target platform for these smaller AA titles.
"We're told Microsoft and Activision's new team within Blizzard is tasked to work on "AA" smaller games based on existing franchises within the Blizzard universes. Given King's mobile expertise, it's possible that these will be mobile games aimed to support Xbox's planned mobile gaming store for iOS and Android — although we're not entirely sure that they'll be restricted specifically to mobile."
However, that's not been confirmed, and Corden was also keen to remind us of Microsoft CEO Satya Nadella's comments this week about a console, PC and mobile approach for Xbox. Here's hoping that if this report is true, Xbox and PC are still firmly in the plans for this Blizzard team and its smaller projects.
As usual, this is just a report for the time being; we haven't heard anything official from Xbox or its teams on this Blizzard news. Of course, if we hear anything more concrete on the matter we'll be sure to inform you here.