That's the main thing I would be interested in also, but I'm thinking that's one thing that we WILL NOT see. That could seriously undercut the need to buy Windows servers.
We're looking at a lowered on-ramp to .net apps that run more smoothly than java+linux+every-support-tool-bit (dev-wise) across devices (and things). It's compelling.
Everything from dev to deployment and ops is getting touched at this conf. This shows where MS's strengths can present differentiation. Their profit source is, and has been, building/selling tools and platforms for others to run businesses. When the thing people hate becomes more like what they aspire to have/be, the tension is palpable.
Google is about the only other player nearly capable. But Google's mission has far less to do with selling shovels vs. harvesting and monetizing.
Apple is just not in this space. If anything, they sure feel like a device-only company in this conversation. WWDC is about the garden. Build is handing out spades, shovels, and, now, dirt.
Xamarin's Evolve, last year, felt a bit like all this does. The are big things happening. If nothing else, at least it feels like change, if not progress for devs and consumers.
The garbage collector for example would be very interesting to peruse. Sure threading and synchronization code would be differ but these have been emulated on Linux before to good effect, I don't see any serious barriers there.
I'm sure the codebase is factored internally to have some sort of platform abstraction.