How to spot (if possible) if a final 了 is part of an omitted 要 in a 要...了 construction or simply a past information?

Question

There are some examples of sentence 了 that indicate future action which (seems to) have a 要 omitted:

我（要）走了，拜！ - I am going to leave, bye!

I know context usually helps with the issue of time and, apart from that, 我走了 is a pretty common sentence that everyone knows it's an about-to-happen action.

My question is:
If I have any other sentence 了 without any context, for example, "我去中国了", is there a chance that a native listener can think it's a future action with an omitted 要 as in "我(要)去中国了" or does the listener definitely knows it's always a past action?

Thanks in advance!

Answer 1

Strictly speaking to the questions,

我走了 is a pretty common sentence that everyone knows it's an about-to-happen action.

Everyone knows it can be an about-to-happen action in the right context. Without any context, however, it still strikes me as a past action as in "讲座你听完了么？""没有，我走了".

without any context, ... , is there a chance that a native listener can think it's a future action

If there is no context at all, there is no way a native listener think "我去中国了" is a future action.

Answer 2

了 in "我去中国了" does not emphasize it is a past or future action in absent of context. Consider the following:

我去年去中国了 - I went to China last year
我明年去中国了 - I will go to China next year

Both are legit and 了 changes depend on the content, althought a native speaker will say:

我去年去了中国 - I have been to China last year
我明年(要)去中国了 - I have to go to China next year

Answer 3

For a future action, there must be 要, 就要. It means "it is the time to do it", not exactly future action.

For true future sense, say 将要.

The key is more in 要 than in 了. 他去中国了 verses 他要去中国了.

If you are the speaker, keep it for safety. Say, 他已经去中国了 versus 他就要去中国了.