I agree with pnorman’s concerns, particular with respect to MapBox’s advocacy here. Coming from other sources this would be more credible. Here’s a comment I posted elsewhere about this suggestion:

It’s no surprise this is coming from an employee of MapBox. Despite their incredible support of the OSM community through technical improvements, they are now a venture-backed company and are clearly looking for a massive exit of some sort. The author mentions Google, but it’s actually MapBox that is best-positioned to basically co-opt OSM and create the dominant interface by which all users interact with OSM. Without ShareAlike, they are likely to begin walling off their data, or (just as well) making the underlying OSM infrastructure pointless in a variety of ways. Imagine if nobody visited or used Wikipedia directly because some other organization basically robbed of it relevancy. At first, it could be fine (Yay! Everything is better!), but in time it could be used to control the data, limit its access, and make the underlying project pointless. This is a possibility if OSM wasn’t SA.

MapBox wasn’t in quite such a strategic position when the ODbL debate was going on, but they were in the community so they could have spoken up then, but I have no idea if they did.

If you don’t believe me, look at the licensing for their formerly-public-domain satellite imagery: http://talkingpointsmemo.com/idealab/mapbox-sells-custom-sat… “The ‘Satellite’ layer may be used to produce derivative data for the OpenStreetMap project. All other use for derivative data is prohibited.”