I'll let the Project Management give you the definitive answer, as they own the product roadmap. From an authoring point of view and end user point of view, there will always be writers whose daily responsibilities require them to create and manage content. Those users want and need to use an XML Editor, such as oXygen. The accuracy of their job depends on it. These individuals know DITA, they know their content and they want the flexibility of the SDL Client tools to create consistent, accurate content. The intent of Draft Spaces is for Subject Matter Expert use. These individuals write content; however, it is not their primary job\role\responsibility within their organization. These individuals typically do not know DITA and do not want to know DITA. They want a way to contribute their content. That way, authors can then go in and curate this SME content and ready it for customer consumption. For the record, this is just my opinion, as my background is technical writing and content management and as a writer, I would prefer oXygen. 

SDL has no current plans to retire the use of the client tools - Publication Manager, Authoring Bridges, etc.. As Pam says, these applications provide powerful capabilities, but also require expert training for professionals to learn and use. Draft Space is designed for faster adoption with Subject Matter Experts that should be working in structured authoring, but do not have the skills or time to learn the client tools. This could mean providing Draft Space to users using MS Word; now they can participate with your Tridion Docs content workflows and reviews as part of the system, not outside.

Draft Space and Review Space open up opportunities to add a new level of users that today may not want to learn your professional author tools. It provides new ways take advantage of the governance, consistency and automation provided by the initial investment in a CCMS.

SDL has no current plans to retire the use of the client tools - Publication Manager, Authoring Bridges, etc.. As Pam says, these applications provide powerful capabilities, but also require expert training for professionals to learn and use. Draft Space is designed for faster adoption with Subject Matter Experts that should be working in structured authoring, but do not have the skills or time to learn the client tools. This could mean providing Draft Space to users using MS Word; now they can participate with your Tridion Docs content workflows and reviews as part of the system, not outside.

Draft Space and Review Space open up opportunities to add a new level of users that today may not want to learn your professional author tools. It provides new ways take advantage of the governance, consistency and automation provided by the initial investment in a CCMS.