Google coming out with a competitor that stacks up feature-wise doesn't fix that for them because it will only run on Android.
Google's going to miss out on a lot of search/ad revenue due to Siri in the future.
However, i think the US readers are missing the most important aspect: how many people in the world can you serve?
This is a system selling feature during a crucial generation. The speed they can rollout new languages, will determine the world market and the long tail, which will prove crucual.
Currently, Google has the best infrastructure to do that, but Apple seems to care more. I live in Holland, for example. No siri, but at least we can buy content from iTunes. Google isnt selling anything but apps in its playstore.
I think whoever is able to actually give me all these features first, wins Holland. Why would it be any different in any other country?
There are markets up for grabs, and the first one to realize that fully, wins.
In any case, wherever Siri runs, I don't think that Internet latency comes close to explaining the latency, and, I think, Siri can actually hide a lot of latency.
I'm not sure you appreciate the issues at play with licensed content. The iTunes Store opened in 2003 and was restricted to the US for over a year. Apple expanded it into international markets very slowly, over several years time, and didn't even move outside the western world until just last year.
My point is that it takes quite a bit of time and effort to address complex international issues with content licenses and rights holders. Apple has spent almost a decade working on this and they're only recently getting to a level of international ubiquity. Whereas Google has been at it for barely a year, but is moving pretty quickly as far as I can tell.