While this is a good idea, I'd prefer it be an option. I always zoom out to max range when running near tracks to avoid trains. So it would be frustrating to go to map mode just by zooming in my case.
Understand. Thats why Supreme Commander allows full game controll independently on zoom level. You can play whole game in map mode if you want to ... BUT thats supreme commander, I know factorio map mode has little specific controls now (could be unified before continous zoom implementation).
The other function for going to map mode, is to examine areas that are far away from the player's current position (free panning without moving the player).
At some point in the game, it makes sense that the player would no longer need to be physically present in order to implement construction. With robotics and a Camera/foreman Bot, any area within a RoboPort's zone should be accessible to the player's control from a Command Center. I could see "Continuous Zoom" as a researchable feature that allows close zoom and manipulation in areas near a Roboport (ie you see and manipulate through the Camera/foreman Bot) and map view only for areas outside of Robot control. For this mode, using the M key would disconnect view panning from the players movement - or something like that.