patrick.net

Reality says

Patricians ceased to exist as an independent class after Caesar and Octavian.

The Patrician class was revived by Constantine. However, there had always been orders of aristocrats and the wealthy, the honorable (medium and large landowners mostly) vs. the humbles (slaves, freedmen, and freemen). They still had financial entrance requirements and were hereditary.

Remember, I'm postulating a long class war that's being lost steadily by the lower classes to the upper classes over time.

Reality says

What Patrician and Plebian conflict would you be talking about in the 5th century? The Imperial rule makers loved the penniless masses in the Coluseums.

Why don't we start with the preceding 4th Century, since the West fell in the 5th.

Increasingly reduced status of the Plebes is signified by several things. First of all, the term Coloni, which originally meant colonists who were free farmers, came increasingly to mean Tenant Farmers / Debt Peonage. Also, the rights of these Tenant Farmers was made more restrictive. After Diocletian, we see a several new laws, including the right of Domini to literally chain Coloni suspected of trying to escape, mandating the collection of taxes due by the Coloni to the Dominus, banning the Coloni from voluntarily switching Domini, and a penalty against Domini who try to entice Coloni away from other Latifundia.

For non-farmers, Constantine (I believe, may have been Diocletian), promulgated laws requiring sons to follow in their fathers' trade.

There are abundant reports of tax collectors being greeted with increased hostility in countryside, reports of poor romans joining barbarian bands themselves (more on this in a bit), and of course a decline in trade, birth rate, and an increase in autarky on the latifunida. The large estates began to produce almost everything themselves, and the landowners spent less and less time in the cities in the West (but not in the East, where they continued to split time between urban and rural).

So here is the birth of manorialism which gave impetus to feudalism. Is becoming a tenant farmer not a reduction in status, both material and social? Is not being required to follow the trade of your father a restriction on upward mobility for many, particularly the lower classes?

Now from the fifth century, here's a bit from Salvian, a Christian who lived in Gaul in the 5th Century, explaining the appeal of going "Native":

None but the great is secure from the devastations of these plundering brigands, except those who are themselves robbers.

[Nay, the state has fallen upon such evil days that a man cannot be safe unless he is wicked] Even those in a position to protest against the iniquity which they see about them dare not speak lest they make matters worse than before. So the poor are despoiled, the widows sigh, the orphans are oppressed, until many of them, born of families not obscure, and liberally educated, flee to our enemies that they may no longer suffer the oppression of public persecution. They doubtless seek Roman humanity among the barbarians, because they cannot bear barbarian inhumanity among the Romans. And although they differ from the people to Whom they flee in manner and in language; although they are unlike as regards the fetid odor of the barbarians' bodies and garments, yet they would rather endure a foreign civilization among the barbarians than cruel injustice among the Romans.

So they migrate to the Goths, or to the Bagaudes (bandits, often mixed barbarian/roman, see Bulla Felix), or to some other tribe of the barbarians who are ruling everywhere, and do not regret their exile. For they would rather live free under an appearance of slavery than live as captives tinder an appearance of liberty. The name of Roman citi'en, once so highly esteemed and so dearly bought, is now a thing that men repudiate and flee from. . . .

www.fordham.edu/halsall/source/salvian1.html

(Italics mine)

Salvian also explains how all the orders of Roman society used "Taxes" for their own personal benefit, and complains about the Roman upper classes and their leadership of Trier.

A piece of evidence that Taxes became an excuse for shakedowns by the upper classes comes from a century prior when Julian was able to reduce taxes in Gaul by to a fraction of what they were, by a ruthless anti-corruption campaign. Only a fraction of the money or goods being paid in tax in Gaul before Julian's campaign was actually going towards government services. Another interesting moment under Julian, was that he tried to expand the Curia, as many well-to-do men were abandoning their civic duties to avoid taxation, because too many of the curia had brought exemptions from taxes by previous governments. The remaining tax burden was heavier because it was spread over fewer and fewer people; unfortunately Julian (one of my favorite emperors, BTW) didn't live long enough to continue this plan.

One also wonders if any official numbers about the soldiers in the limitanei and the mobile forces can be trusted, since we have abundant anecdotal evidence that high ranking officials often put many non-existent soldiers on the payroll, from which they drew a little 'extra pay'.

Another reason I believe the West collapsed and the East didn't is that Latifundia were more common in the West, Western Latifundia pursued a policy of self-reliance, we know that trade in the West declined and piracy resurfaced in the crisis of the 3rd Century (and flourished throughout the dark ages). And most important of all, the East was always more urbane, more commercial, and more 'industrial' than the West. In the past century several digs in the Levant, uncovered a increasing prosperity and growth of both cities and rural villages during the 300s-600s. In fact some places continued to grow after the Arab conquest.

There is every sign of a great FU-based decentralization (mostly in the West) taking place after the Thirty Tyrants and accelerating into the 4th and 5th Century.

One might even say, tongue in cheek, that the Romans decided to "Go Galt". The poor to avoid shakedowns and proto-serfdom from the Domini, and the Domini to avoid their obligations to the Roman State and pocket the tax money for themselves.