“Will Jay have left work already?”: the future perfect

Question

It's said that the future perfect (will + have + past participle) is used to say that something will be completed by a particular time, as in

1. By next summer I'll have finished my degree.

But in the example

2. It's 5.30. Will Jay have left work already?

it seems to me that the second sentence could be replaced by

3. Has Jay left work already?

which is of the present perfect tense, without any significant change in meaning.

Please let me know if I'm correct.

Answer 1

You are correct.

A possible nuance is

Has Jay left work already?

is a normal unemphasized question, whereas

Will Jay have left work already?

might have the feeling

Will Jay have left work already?
I can't believe, has Jay left work already?