Firs of all, just because CMA is stupid, why Shania should drop half of her fanbase (even more) and market? True, the States is only one country still half of Shania's fanbase and sales are coming from there. The other half is from Canada, Europe etc.
Not to mention, that the music is she's playing. She just recently said, she's a country singer. I don't see any good reason to leave that market.

Anastacia another example. She purposedly (spl?) made music which is going very well for Europe, because couldn't break out in the US.
Look at Robbie Williams, he's huge everywhere else, mainly in Europe, except the US, and he's trying but failing to get in.

Each market has its positive and negative sides.
Without the US market backing her, Shania will be seen and judged with other eyes in Europe. Now she's for them someone good, but her music is "american".
She's doing great in German speeking countries and UK, but less good in other places.
For being based in Europe she'll have to change her music, to fit it to that market.