How have you been doing [getting on, making out] since?
それはその後どうなりましたか?
それはその後どうなりましたか。
How have you been (getting along)?
What then?
What became of that after wards?
What has become of him?
彼はその後どうなりましたか?
What happened to him after that?
What has become of the matter?
What is the sequel of the story?
あの二人はその後どうなりましたか?
What happened to those two after that?