China’s kingmakers may have decided to play safe for now, but leadership issues will again loom large in 2017 when the party’s next five-yearly congress is due to be held. By then the newcomers to the standing committee will be considered too old to carry on. Some of the powerful elders might have faded from the scene. Mr Xi and Li Keqiang might then have a freer hand to promote their own people, and perhaps more daring ones. If, that is, they manage to keep control until then.
I know that the last sentence of means "it is possible only if they manage to keep control until then" or "it's impossible unless they manage to keep control until then".
But I don't understand how the sentence functions: what does "that" refer to, or is it just an empty word refering to nothing in particular?
It is not until 3am that they returned home
I think that "it" refers to the fact that "they returned home", and that the above sentence can be rewritten as "the fact that they returned home is not true until 3am." This sounds wierd but has helped me to understand the sentence's functioning. But some people tell me that I shouldn't comprehend the sentence this way because "it" doesn't refer to anything. Am I really wrong in my understanding of "it" in that sentence? If so, how do you think I should understand it?
So everybody thinks that is is short for that is to say? But I really think that it means anything but that is to say. Before I asked this question I had tried to comprehend it that way, and noticed an absolute logical error: since that is to say usually connects two grammatical constituents expressing a similar meaning, the two constituents should be of the same pattern. That is to say, if the previous constituent is a statement, then the following one should be a statement as well in spite of all its clauses and parentheses. But in the above excerpt, that is is linking a conditional clause with a full sentence.