FumbleFingers is correct that, semantically, there's very little--if any--difference between are hoping for and will be hoping for.
It's not be itself that signals the future, it's will be plus the present participle that signals a future progressive action; but with the progressive tenses, there is generally already a future aspect involved (i.e. they are continuous and often project beyond the present).
So yes, in answer to your question, it's phrased as will be hoping because it points to a future action. And it's specifically hoping because of the progressive aspect.
There's a reason for the use of will be hoping rather than are hoping, and that is that the statement is to some degree conditional (i.e. it hinges on Mike Devereux heading the committee) and also, as you've noted, is speculative. The workers' feelings or hopes will be brought about when/after Mike Devereux assumes the lead of the Productivity Commission in other words.
It's speculation about exactly what feelings this change will bring about written by an outsider.
Revised as if the author is speaking for or is one of the workers:
Holden workers are hoping for some direction on the company's future
as company chairman Mike Devereux fronts the Productivity Commission
in Melbourne today.
That's a much stronger statement.
Revised entirely in present tense:
Holden workers are hoping for some direction on the company's
future now that company chairman Mike Devereux is fronting the
Productivity Commission in Melbourne.