Hi,
Currently the ECW format is only supported through the ArcGIS Runtime Local Server. Direct support in ArcGIS Runtime is on the roadmap for a future release, but unfortunately not in the June-July time frame you mentioned above.
Make sure you enable ECW support when creating the ArcGIS Runtime Local Server deployment via the `ArcGISLocalServer.AGSDeployment` file (created in the root folder of your project after referencing the LocalServices package and running a build):
e.g.
<Package name="Additional Data Formats" enabled="true">
<ChildPackages>
<Package name="Raster" enabled="true">
<ChildPackages>
<Package name="ECW Rasters" enabled="true" />
Cheers
Mike