According to Shum, Windows 10's new "hamburger" menu (dropping down from the top left), works well as a "home" menu for an app, but is apparently less useful where there's no point in it being there. The design team's intent was to ensure universal apps, as well as an adaptive user experience which will allow a certain degree of free: swipe controls on mobile, but a better focus on keyboard shortcuts and mouse control on PC iterations.
Long-established design decisions (at least in Windows), like the location of Internet Explorer Edge's address bar, remain the subject of experimentation. The team is apparently exploring design options here too, but for now, the address bar still resides at the top of the browser. And if you thought that the mobile iterations of Win10 were looking a little, well, rough around the edges, the team lead added that "what you're seeing today are apps only partially-adapted for the phone UI that we intend to ship when [it's] finished."
It gets a little bit more complicated when the operating system's mobile and PC iterations go in different direction. While switching between tasks on PC-based Windows has typically left to right, with mobile it's the opposite. Is Microsoft going to over-rule one standard design practice for another? Maybe. "We want to have a good understanding of how tough it is for phone users to relearn before we make a final call." Given that Windows PCs outnumber Windows Phones, it may be an easier call than you'd think.