In the past (3.x API) I relied on the map before-unload event to perform cleanup, capture state information, etc. For example, detaching listeners and other event handles, capturing the last basemap in use, capturing the last zoom/center, etc. before-unload worked very well for this purpose.
Is a similar event on the horizon or envisioned for the Map (or Views) in 4.x? I find myself struggling to find a convenient place to perform these activity that doesn't result in callbacks firing far more frequently than the need to.