The whole Realms continuity would not be much of a problem with having Kara-Tur as the default OA setting. There were very few references of Faerun in Kara-Tur supplements and vice versa (though Kara-Tur has more mention in Faerun than the other way around). I don't think it would matter much if even it had up to 25% Faerun references. Because I believe a lot of people use Greyhawk not just as the canon campaign setting itself, but also as the default of setting for their homebrew games. The same can be done with Kara-Tur. Heck, Kara-Tur was supposed to be originally part of Greyhawk, but it was obvious from the start the place was supposed to be the generic default campaign for OA settings as well.
The most Faerun talk I have seen in all the Kara-Tur products was mention of the Hordelands tribes, trade routes with Faerun, Elminster speaking with that spirit dragon guy (long name, I think a shortened version was Mei Ling?), a cult of Chauntea worshipers in the nation of Wa, spelljamming ships created and owned by the nations of Shou Lung and Kozakura and I believe that's about it.
One thing is for sure, Kara-Tur was huge. They even covered parts outside of main Kara-Tur in one of their adventure modules, closer to the center where Faerun, Zhakara, and Kara-Tur meet. If anything, it deserves a book the size of the FRCS all of its own. Beef it together with OA, and you have the OA setting you dreamed of.
The most Faerun talk I have seen in all the Kara-Tur products was mention of the Hordelands tribes, trade routes with Faerun, Elminster speaking with that spirit dragon guy (long name, I think a shortened version was Mei Ling?), a cult of Chauntea worshipers in the nation of Wa, spelljamming ships created and owned by the nations of Shou Lung and Kozakura and I believe that's about it.
One thing is for sure, Kara-Tur was huge. They even covered parts outside of main Kara-Tur in one of their adventure modules, closer to the center where Faerun, Zhakara, and Kara-Tur meet. If anything, it deserves a book the size of the FRCS all of its own. Beef it together with OA, and you have the OA setting you dreamed of.