To be fair, the blue camp was also making these kind of claims during the ABK legal stuff as an argument against the acquisition.
But in reality none of that was looking at the base issue, and neither is this thread or the Gears of War stuff...
MS made that ABK purchase amongst others not to win the current console war, but to win what comes after - probably cloud streaming. They're still well positioned to do that with the studios and IPs they have. So while Sony makes hay now on PS5, what the future of gaming holds is less clear.
But as things stand MS are still in a strong position going forward as a result of the ABK and Zeni purchases. If they hadn't made those acquisitions, I believe they would have started to wind down the xbox division as a whole by now.