I think it could be useful to provide a tiled map service API for ArcGIS Server Image Services on the ArcGIS Open Data Portal in addition to the GeoService API. A tiled map service usually appears in the format http://example.com/tiles/{z}/{x}/{y}. This is possible with MapServices like http://example.com/arcgis/rest/server/ServiceName/MapServer/tile/{z}/{y}/{x}. The benefit is that developers could easily use open data image services directly in their Leaflet, Mapbox or OpenLayers applications.
However, using an Image Service would be requiring some sort of server proxy like GitHub - JasonSanford/tileify-ags-proxy: Fetch slippy map tiles from ArcGIS Server to create tiles from the image service. I'm not sure if Esri would be interested in hosting such a proxy?
