Ok, first while many app makers are American, does it really matter if they are selling their app worldwide? Simply put...no. Short term it does, because you start at home base and what the largest target market is. But, most apps are already made. What you get now are mostly new niche apps, the one millionth fart app, and new games. With the big game engines now supporting WP, most companies are going to port their games to all three platforms to maximize their sales. The app issue isn't going to remain an issue for much longer. We keep getting a bunch of new WP apps that are coming from the other platforms. Who thought Mint was ever going to actually make it? Or Instagram? Vine? Subway Surfers? Temple Run 2? And many others.
As far as the tablets go, netbooks did the minimum things that Chromebooks do. This is no different. The problem is, and always will be, that people have this "thing" sitting there that they want to get use out of. At some point they decide they want to try some application they heard will help touch up all those crappy iPhone photos they have. Then they find out they need a Windows PC for it. Oops! With netbooks it was "need a computer with minimum specs that are better than this POS you bought!" As tablets like the Dell go on sale, as they did this holiday season, for $199, the game totally changes. When someone comes in and sees a Galaxy Tab 3 for $249 and a DV8 Pro for $199 on sale...gee...what do you think they are going to buy? Hmm...I don't know...
If you think the Dell Venue 8 Pro is under powered, then you either are expecting a workstation/gamer PC class product, or you haven't used it. Businesses are going to flock to tablets like these. Why go through all the BS of the iPad, or all the security issues of an Android tablet, when you can simply buy Win 8 tablets fro $300 or less (a large business could probably get large orders filled at the kinds of prices we saw these things on sale for)? If they buy a Win 8 tablet, everything works like the PC's. No additional administration costs, nor training, nor learning curve...it's just a mobile PC without a keyboard attached. It's perfect for a corporate officer on the go. As Android's/Chrome's cost advantage erodes, which we are already seeing in the WP market, and people can get Windows tablets and phones and keep everything simple, powerful, and fully connected (which is what WP 8.1 will start to do) Google's offerings become redundant and a hassle.
The same people telling us that Chromebooks are going to thrive, are the same ones that kept telling us about Linux on the desktop. The average consumer isn't a techie, and they are often the ones that aren't overly satisfied with Android and often end up going to iOS in the past, and some are now going to WP.