If you want us to target Metro, you're going to have to fix the API so that we can do basic things like query for the number of CPU cores on the user's machine.
Presently, WinRT offers me no way to determine how many threads I should create to make good use of the CPU. I will fail certification if I use Win32::GetLogicalProcessorInformation, and Win32::GetNativeSystemInfo only tells me the number of logical processors, which does not distinguish between physical cores and SMT/Hyperthreads. Please see your own documentation (DirectX sample "Core Detection") for why it's important to have the correct count.
You want me to support Metro, but Metro doesn't support me -- not because I've fallen behind the tech curve, but because Metro doesn't support state of the art. State of the art means multicore, and in order to do multicore correctly I need to know how many threads I should create for the user's CPU.
Until such basic functionality is made available to the developer, I must conclude that Metro simply isn't "for" real heavy-duty PC games. Metro is for phone games and tablet games.
If I sound frustrated it's only because I've chased down this glaring oversight in the API already on your dev forums and on User Voice, to no avail. The official response was, "Yeah, it's not possible to do this". Well, OK then, as long as you understand what you're really saying is that it's not possible to put an actual, modern game on your new platform.