Love OSMC. There is one thing I wish it had was a “startup loader”, kind of like a boot loader for operating systems, except, it’s more a “what are you using the Pi for?”.
By default: OSMC loads as is does now.
But add an option for a user customized selection of start-up choices. Choices such as, terminal only and X11 (if installed) for common choices, but also allow the user to create custom choices, like Only Be a NAS Drive or Only be a Mumble Server, etc…
Note: You should try to do this though runlevels, it’s a way I think for X11 and Kodi to play well together… You should switch run levels when switching from using Kodi, X11, or Terminal only, the three most desired choices no mater what custom menu options you make.