Dragon isles made sense in cata. COULD have been part of MoP. Even in WoD WHo knows.
but since Legion dragon isles made no sense..
tinker class could be done without dragon isles, and ones more could have made since in BFA with mechagnomes but yea, tinker class is dead in the water.
Edit: ALso Why would Dragon isles introduce Tinker? I cant be Bothered to find it now, but there been done some amazing Dragon-ish classes, Where your Specilations would be like Red or green dragon for healing, Black dragon for tanking or meleeing, And then maybe Bronze for something else. Or Red for ranged, or what have you. But that owuld make so much more sense, in a Possible" dragon isles" expation