Imajin's right.
And to make the Roman Empire last longer, you'll need a much earlier and far more radical POD.
Such a POD could be that Flavius Aetius was not assassinated by Valentinian III, or that the Huns were stopped during
their invasion of northern Gaul, or that the Huns for some reason never reached into Europe in the first place.
Keep in mind that saving the Latin part of the Roman Empire pretty much requires preventing the great migrations
of the Eastgermanic peoples into Roman territory (which was caused by the Huns invading eastern Europe).
If these migrations aren't stopped, then it is highly unlikely that the existence of the Western Roman Empire
can be prolongued for more than a few decades, or at most centuries.
And even if it survives for a long time, it will still be just a remnant of what it once was, propably covering only Italy, Illyria and Dalmatia.