Earlier quoted context omitted.
I doubt there will be a native GUI renaissance, look at the mac app store, it's not making a dent in the global direction and it's available since years. Ok it's only for a single platform, it's even worse on the windows app store! I think there is no way back for desktop apps. Browser is the best sandbox available.
VM hypervisors are even better sandboxes. I don't imagine any browser will be more secure than for example a VirtualBox or VMWare VM, unless the browser itself literally is a VM hypervisor.
Browser is maybe not so common compared to hypervisors on end users computers?