People are going to want to host thier own osm layers using osm technology. they are going to want to have control over the license, the users the edits and the rendering of the data. they are going to want to import layers of data and maintain them separately. these layers will be shared under certain terms with other people, and edits to them can be suggested. They will want to be able to publish tiles or subsets of the data. The toolkit will need to be able to support all these things.