Lots of changes are planned for Eeschema but “polygon selection” is not one of them. The user experience will probably be very different, so maybe you will not miss this particular feature as much as today. I think shift+click will be supported to select multiple items, like in the new OpenGL canvas of Pcbnew.
This would be a useful feature for me. I know it’s been a couple of years since this post, any chance it has been implemented in that time?
Very much enjoying KiCad, i’d go so far as to say it’s a triumph for open source software. I would consider assisting in development, or submitting patches, though i realise this may not be a trivial thing to implement.