Idea Summary
It would be really nice having a React like app experience while navigating between apex pages without full page reloads. The user experience improved quite a lot in apex 5.1 when not needing a full page submit for executing validations. Something similar is achieved with modal dialogs now, when only the content of the dialog is loaded and anything else is kept without reloading. Even implementing this with iframes would be a nice thing. It would also allow to set page transition animations.

Use Case
Improve user experience while navigating between pages.