I doubt the first thing on the minds of people at Marvel when they were brainstorming Doctor Strange was how they would avoid causing controversy with China. They will never admit it, but they wanted Swinton from the beginning. In fact, according to her:
http://www.babysavers.com/tilda-swinton-doctor-strange-and-working-with-marvel/
That whole thing about the controversy with China was just Marvel's way of getting out of all the accusations of whitewashing.
I was in a very fortunate position of not auditioning at all. I was working in LA and I was told that Scott Derrickson wanted to meet with me.
We had tea and he told me he was going to do this film. He told me, Doctor Strange is going to be a big, tent pole Marvel film about creation, not about destruction.
Then he said that he had written this part for me. He said, If you don't do it, I'll have to rewrite it. So I was flattered and honored and intrigued. Then I read the script and I felt really good about it. I was very lucky.
http://www.babysavers.com/tilda-swinton-doctor-strange-and-working-with-marvel/
That whole thing about the controversy with China was just Marvel's way of getting out of all the accusations of whitewashing.