> "Mouse-over" for more info is not meaningful for touchscreens. So icons can't have explanations.
I suspect the period of not having a decent UI for surfacing alt-text (on web) or equivalent help for native apps on mobile devices is probably not going to extend long into the future. I don't know what the UI convention will be (gaze tracking? light-touch with pressure sensitive screens? some gesture?). Touch UIs are (despite being ubiquitous with the explosion of the last decade) still relatively immature.
I suspect the period of not having a decent UI for surfacing alt-text (on web) or equivalent help for native apps on mobile devices is probably not going to extend long into the future. I don't know what the UI convention will be (gaze tracking? light-touch with pressure sensitive screens? some gesture?). Touch UIs are (despite being ubiquitous with the explosion of the last decade) still relatively immature.