It won't be an Aperture replacement, but I'm very curious to see what editing plugins will appear once El Capitan is released. Serif software has said they intend to release a Photos plugin for Affinity Photo. We'll see what all the others do, and if it allows for some non-destructive editing.
Like everybody else, I'm extremely disappointed with the Aperture situation and how it was handled. Yes, if they wanted to devote developers to it, they could upgrade Aperture to support the Photos library, but that is just one of many things needed. They've chosen to focus on a mobile strategy at the expense of Pro users.