I may have a semi-universalist view (And yes, I know how old this thread is, just thought I'd throw in my two cents.) Two me, while I am mostly folkish, I would include the Celts, Uralic peoples, and even some of the Slavic people. The Gods of most of Europe are very similar, mainly between Germanic and Celtic people. Two me, Celts and Germans are almost the same, and in my eyes they have the same blood. The Celts and Gauls were said to have crossed the Rhine and spread into Western Europe, while the Germans stayed, so to me, they are Germans as well. Also, Russia was once ruled by the Vikings, and many Vikings assimilated with the Slavs, so many Slavic people have Nordic ancestry. The same goes for the Uralic people, as Sweden controlled Finland for a long time. I am one quarter Italian. The rest of me is all German and Celtic. I think nowadays it's very hard to find people of pure Germanic ancestry, so I don't sweat it too much. The only think that would strike me as odd would be an African, Asian, or someone from the Middle East "converting" to Asatru. And like Zephyr, I wouldn't consider them Kin, but I wouldn't have a huge problem with them. To me it would just seem odd.
*Edit:
The way I look at it, if your Ancestors had Heathen Blood(Germanic, Celtic, Uralic, Slavic), it would not strike me as odd if you took up Asatru. When you look at it, Germanic Paganism is a blanket term, because there is no dogma or any set of "true" beliefs. Each tribe and family had different beliefs. They all had things in common, but they differed, much like the Celtic and Slavic Gods and beliefs differ from the Germanic. So I think that all Heathens should join together under Heathenism, and try to bring it back, rather than fight between each other on the differences between their beliefs. We can all have separate beliefs and still be Kin. I don't think that my Gods would have a problem accepting another Heathen of any sort. Slavs, Celts, and Germans are so similar in my view that I don't think they should be considered that different, so much as to exclude them from my "folkish" view. After all, Germanic peoples have spread all over the world. England, North America, South Africa, New Zealand, Australia, Russia, Finland, Poland, Czechoslovakia, France, etc.