As sure as anyone can be about features in a beta making it to the released version. And you can right now delete all the photos from your photo stream and then upload only the ones you want.
Right now you have to login on your computer iCloud.com and reset photo stream. Then go into photo stream settings on your phone and turn it off, then turn it back on. Once you do that all your photos will be deleted. Unfortunately we can't delete individual photos. It's either all or none.