one point, regarding development, is clear. one core for the app, coded one single time, then, design customizations for each OS variation (+ MAYBE specific additions, like phone dialer for phone OS).
a second point is regarding deployment. i dont believe that every developer or studio will be amazed and app will start to "rain" in our stores. there will, almost surely, be 3 situations:
1st, developers who have their wp app and always wanted to build a windows app will be more encouraged now, so they will maybe build it. but here is also a catch. i think more apps will come from phone to desktop, bacause of the same os running on tablets.(maybe vice versa too, from desktops to phones, but still because of tablets)
2nd, one app may be mainly for phone or pc, so even the small, but still needed, tweaks to convert it to universal and deploy it on all stores will be too much of a resource consume,at least in a first w10 era, given the small possible users increase from the other os variation. here is also a catch too: some apps from this category will come universal over time. one day, after several updates, they will see their app so close to universal so that those customizations for mutiple store deploys would be insignificat so they wont see it a lose from a the resource consumed/new users aquired perspective. (also, in this category are the apps which will continue for a period to run multiple apps, each for their store, too)
3rd, some apps will never be available for every device, even after some big time when they will eventually already had enough updates to the code so they would be almost universal. some apps are for phones and some for pc, period. not all of the apps need to run on every single device. maybe tablets will do something on this category too, but still, there for sure will be one day when some app will be universal at their core but unpublished for every device type.
sorry vor typos and bad english
