I don't think getting Intagram, Vine and Flipboard will be enough, but it sure was a coup announcing them at Nokia World. We need more developers considering releasing WP versions of their apps alongside their Android and iOS versions, which is really difficult to do especially for small programming teams who most likely would have to choose one platform to start with.
Re: "mobile race/war": In the case of WP, adoption is crucial. I am choosing to support WP even though it doesn't have some of the more mature features that Android has because I'd like to have more choices once mobile tech matures. I don't want to be stuck choosing between a company that puts ridiculously high prices on their overrated devices, and another company whose primary business is selling ads. I personally would rather have a third choice, and WP just happens to be a perfect choice for me. From a developer POV, the UI is very promising and provides the most functionality, especially as we get better screens and SoCs, icons just won't be able to keep up.