Future perfect tense:

He will have left ...

(Irma, no estoy seguro como acabar la traducción. ¿Significa que habrá salido ya de la oficina (o lo que sea)? No recuerdo haber visto jamás "salir de" + infinitivo).

"Salir de trabajar" significa "salir del trabajo".

¿A qué hora sales de trabajar? = ¿A qué hora sales del trabajo?
¿A qué hora vas a trabajar? = ¿A qué hora vas al trabajo?

In Spain is more common to say "de/a trabajar".

will have left the office already...

will have come out of work already...

Is it correct?

I understood the future perfect expresses probability, so it could mean

He must have left the office already.
He must have finished work already.:)

I'm with Perikles here. "Habrá salido ya de trabajar" suggests an assumption, unless the context says the contrary.

So, something like "We want to catch the 6:30 movie. Habrá salido ya de trabajar. Therefore, we should make it on time." ???

So in this case, the "habrá" is part of the participle (paired with salido) and not necessarily part of the "hay" usage?

It is just a straighforward use of haber for a future perfect. I don't see what it has to do with hay, although Irmamar said it was, and I wouldn't dare to disagree. :D

Of course you must disagree ;)

I was writing about possibilities the verb "haber" has . One of them is as auxiliar. The question that the future perfect is used to make a supposition is another topic ;) . Anyway, it all depends on the contexts, because I could say:

Habrá salido ya de trabajar cuando llegues a casa.

In this case, it's not a supposition.

"Hay" is related to the verb "haber" because it's a form of this verb conjugated. I wanted to make a distinction of the use of this verb, that's all ;)
:)

Yes?

Debe de haber salido... (probabilidad) ;) :)