Love Lorna's post and yes Terese to quality through collaboration - my experience is that both carrot and stick needed for this to happen.
On sustainability (mentioned last night in the Video for All webinar and also the subject of a collaborative paper I'm involved in) when related to teaching practice all "actors" need to see relative advantage. I am currently battling with this myself. There are platforms I use to share my materials but they often do not display CC licences as I would like. (eg. slideshare) Our institutional platforms are not very open on the whole and others I have used are now unable to cope with the technical changes that have happened so rapidly of late (scorm - really?). I am wary of companies claiming to provide free hosting in return for passing over materials. I think this initiative is interesting https://reclaimhosting.com/
Like most I guess I am feeling my way but to me OEP is:
-a way of thinking beyond the immediate
-a contribution to teaching practice and learning