A good solution to the iPad’s multitasking problem from Ryan Christoffel. In short, he thinks the long-press contextual menus that appear on app icons should include options for split view and slide over. I think this is a great idea, but I’d still be concerned about discoverability.
I hesitate to advocate for an omnipresent menu that could be used for these type of system functions, but I’m not sure how else you could include advanced features like multitasking in any other way without always dealing with issues of discoverability. At least with a consistent button in the system status bar there would be something indicating that options are available.