As it has already been said in the Plasma mailing list, we’re planning the next iteration of the KDE Workspaces.
For this project, we’d like to start with gathering a group of people to figure out a vision for this next iteration. If you know you have good ideas and you want to be part of this group, please send me an e-mail to aleixpol@kde.org and we will condider your application.
Anyhow, if vision is not what you want to work on and you still want to help, also there’s plenty you can do, just read through the e-mail and you should already start to get some ideas.