It's definitely the way to go for the bigger tech companies. By taking chip design in-house, they can create their own closed ecosystems that createlock-in and ensure returning revenue in future.This also means that semi-conductor manufacturers will be in high-demand - time to buy!
I don't think an app store from Microsoft will make much of a difference. The Windows ecosystem already doesn't rely on one. Adding an app store might serve to hurt its platform instead, since Windows applications are already so widely and easily available.