The development is pretty early, certainly before any time you can reasonably call 'Byzantine'. I suspect it's not really changeable unless you'll shift some big social developments. I can't really see any way that Roman art is going to remain static, and naturalistic pseudo-realism (Greek classical art isn't realistic, it just looks that way) was already a 400-year-old academic tradition by the time of Augustus.
What might help is somehow heading off Neoplatonic thinking (though it probably won't be enough to off Plotinus). An important element in Late Antique art is a tendency to essentialise and emphasise spiritual aspects at the expense of the physical. You'd still see some kind of change away from the Hellenistic way of doing things, but it might be a different, more naturalistic direction.