I expect it will be considerably less than 2 years, though more than 2 months, before the next flight. However, one interesting aspect of modern technology is that you can simulate things a lot more realistically than you could 40 years ago, so if your purpose is guiding technology development, many fewer flights are actually necessary.

Here's an interesting thought for you all - since Shenzhou seems to almost meet the requirements for OSP with reasonably modern technology - what do you think NASA's response ought to be if the Chinese bid for the OSP contract? Could it happen? If not directly, then why not via an intermediary US company? By the time the OSP is supposed to be ready for flight tests, Shenzhou could well have an established track record. We buy an awful lot of other things made in China; why not space flight hardware?