The only way to do this currently is if you simultaneously published a hosted map service and hosted feature service at the same time (from ArcMap). You would use the hosted map service for the non-editing case.
We are looking into adding the ability to disable editing of feature service layers inside a web map. Thus, you would then create one web map for people who need to edit the layer and another for those that don't. This feature may be available by the end of the year.
Thanks,
Mike