For Fedora 23 we're already looking at possible features of Fedora becoming more atomic-like and potentially shipping GNOME Wayland as the default desktop experience rather than an X.Org Server and potentially defaulting to the Btrfs file-system by default.. There's also been pipe dreams of going 64-bit only and switching away from Firefox as the default browser.
In terms of new feature proposals that are moving forward and will be evaluated by FESCo, the new Fedora 23 work presented thus far are:
Disabling SSL3 & RC4 By Default - They'd be disabling them in the name of security.
Perl 5.22 - Incorporating the latest stable release of Perl into Fedora 23.
There will certainly be many more features being proposed for Fedora 23 in the weeks ahead, so stay tuned!