This is much bigger than Call of Duty - everyone is just so short-sighted. Call of Duty is the loss leader for Microsoft. But, as an IP, it is somewhat limited so it's ok to pimp this out. This will be Microsoft's Madden, because they will lose more money by limiting it to one platform.
Cross-platform support and play will be a keystone strategy, because they get to plaster Microsoft Gaming everywhere.
- World of Warcraft on consoles (work has been underway for a while to add direct controller support). And this gives Microsoft instant access to a competitor to Sony's FFXIV. Plus Hearthstone can compete with Wizards of the Coast, and Heroes of the Storm gives them a League of Legends competitor.
- Overwatch, combined with Call of Duty and Halo, will lead the way for Microsoft Gaming to have an eSport division for gaming.
- Starcraft - eSports. It gives them something to add to their strategy games stuff, and I would imagine that it's not going to be too difficult to integrate aspects of Starcraft into Halo (or vice versa).
- Mobile games division (Candy Crush) - with access to a division that knows how to profit off mobile, Microsoft can bring this to other games (or other games to Mobile while profiting - something Nintendo screwed up royally and Sony has no clue how to do).
- Crash Bandicoot and Spyro will give Microsoft new mascots to work with, on top of Minecraft, and allow them to attract younger gamers. This has always been a problem for Microsoft - they've always managed to appeal to young adults / new adults, but teenagers that are the target audience of Nintendo are hard. This segment of the market is much more profitable, and increases mindshare for Microsoft.
It's not hard to see how this fits in the overall Microsoft Live streaming strategy, because in the future, it will be about streaming games and less about the hardware. In order to stream games successfully, you need IP.