No they're not buying another dev so settle down, instead they have entered into a partnership with People Can Fly to develop a new AAA game with a budget of somewhere between $30-50 million codenamed project Maverick.
Some interesting tid bits...
Development of the new game will be "performed under the work for hire model" and is based on "the intellectual property rights owned by the publisher.
So MS will publish and own the IP, and i'm not sure what the "performed under the work for hire model" is.
Anyway i'm probably one of the few people on here who liked Outriders, but I didn't enjoy Bulletstorm, so their games tend to be hit or miss for me but will keep an eye on this.