My guess of what they plan to do with motorola, pure guess mind you
1: Strip out its software team, keep only those required after all, android is maintained in house, they can easily gear the base software to work for the motoroloa hardware.
2: Strip out the hardware team, limit the number of products on the market. After all motorola is basically competing against apple and google. I can see them limited the handset numbers and using motorola as more of a demo company. "This is how android phones shoudl be made" with like, one high and one low end model each iteration of android.
3: Gradually absorb motorola and turn it into google mobile.
Why? Well, laying off half the hardware / software team means lower costs, and the more experienced members they can always move on to android development rather than letting them go completely. Fewer handset types being released means fewer stockpiles and although this means less gross profit, the net profit would probably improve, and that's the figure which matters.
As for merging it totally into the google brand, well, that's just less in the way of advertising costs, and we all know how much google loves a unified brand. I'm honestly surprised they didn't rename youtube to googletube.