Looks like a FBX-to-glTF converter has sprung up recently (linked from the glTF repo README: https://github.com/cyrillef/FBX-glTF). I have no experience with it though so I can't say how well it works.
> glTF on the other hand - and please enlighten me if I got this all wrong - is asking engines that already have their own tailor-made runtime format to support this one as well (or even instead). That's asking a lot.
For our Superpowers game maker, we didn't end up using glTF as the actual runtime format but we have a fairly simple importer that reads glTF, scavenges for what it needs and builds the final data. I expect most engines would still need a "last-mile" conversion, still some processing but much simpler than working with COLLADA or FBX directly.
> glTF on the other hand - and please enlighten me if I got this all wrong - is asking engines that already have their own tailor-made runtime format to support this one as well (or even instead). That's asking a lot.
For our Superpowers game maker, we didn't end up using glTF as the actual runtime format but we have a fairly simple importer that reads glTF, scavenges for what it needs and builds the final data. I expect most engines would still need a "last-mile" conversion, still some processing but much simpler than working with COLLADA or FBX directly.