Rome, the past and future

As my year 12 class has studied Aeneid VIII this year, we've been looking at how Virgil represents Rome's past and future (ie the future from Aeneas' point of view. For Virgil it was the present, for us it's the past.). It's easy to spot references to the Rome of Virgil's day as you read Aeneid VIII, but it's more difficult to explain Virgil's purpose in doing so. I recently read an article which, I thought, expressed it well. Talking about the "interweaving of present, past and future" it says:

‘One of the themes of the book is the union of different peoples. The Trojans, the past inhabitants of Italy, fuse with her present inhabitants into a future people, the Italians. The fact that Evander anticipates this development and thus speaks of “we Italians” (VIII, 331 f.) is not one of Virgil’s “inconsistencies”, but serves to underscore this theme explicitly. A last example of this interplay of the various time levels may be taken from the Hercules-Cacus episode itself. Evander speaks of Hercules’ adventure as if he and his men had been present (200-1):

attulit et nobis aliquando optantibus aetas
auxilium adventumque dei.
It would seem, then, that Evander, Hercules and Aeneas were contemporaries. This was chronologically untenable, and thus the event, represented first as contemporary, is later projected into the mythical past (268-9):

ex illo celebratus honos laetique minores
servavere diem.
On a different level, the et nobis may well refer to Vergil’s contemporaries, the god whose advent is being celebrated being Augustus. Thus the line between past and present is again blurred, and the “Augustan future” is superimposed on the original time level.’

[Karl Galinsky, "The Hercules-Cacus Episode in Aeneid VIII," AJP 87 (1966) 22 f. Thanks to James for recommending this article.]