I disagree. Swift and its accompanying libraries are designed for automatic reference counting rather than tracing garbage collection. I think that's a big deal for mobile apps (see Drew Crawford's take on GC in mobile apps, http://sealedabstract.com/rants/why-mobile-web-apps-are-slow...). In that light, Swift projections for WinRT would be great.
Swift only has reference counting because it made sense as the language shares the Objective-C runtime.
Objective-C only got ARC because Apple never managed to make their GC work properly without crashes in the context of Objective-C code, given its C underpinnings.
CS literature is full of examples on how to achieve performance comparable with GC with reference counting, the solution ends up being a mini-GC anyway. And reference counting cannot compete with GC implementations in lock free algorithms, even with deferred counting.
Swift won't bring much anyway.