Its sounding more, and more like a behavior.
Maybe. Thing is, it wouldn't make sense pairing it with anything other than sprite...so why not just bundle it in with sprite? I like the idea of an enable/disable tiling toggle.
Just Keep the TBG for overall coherency and backward compatibility.
Once the tilable option was added and the bugs worked out, TBG could just 'disappear' from the plugin list. However, it would still be in the plugin folder, and loading any old projects would just load it in (though, perhaps C2 could provide a message that TBG's are now obsolete, and highlight TBG object in red or something).
Any new users going to add TBG's wouldn't be able to, and will head to the forum and find that they can use sprites instead.