Consider adding support for FeatureServices

[rowanwins]

Various Esri Services (name FeatureServer and MapServer) can be queried to return geojson which can then be displayed on a map.

To do this naively is quite simple, you can just pass in a query parameter &where=1=1, this gives you back all the data. The problem is that the response size could be really big depending on how many features there are.

A more sophisticated approach uses getting data on a per-tile basis, this is how esri-leaflet tackles it. This approach is alot more scalable as you only retrieve the geojson for the area you're looking at, and you can also adjust precision and simplicity depending on scale etc.
This would be awesome, but requires writing a custom-source for mapbox-gl, and this is somewhat undocumented, and would require a stack more code.

Choices choices....

[rowanwins]

Implemented in https://github.com/rowanwins/mapbox-gl-arcgis-featureserver