One thing that is probably important - not immediately but the sooner the better - is something where the Roman economy in the west develops more. I'm not sure how, but that would become a problem as Italy faded relative to the other areas in the empire.
I don't know if that is possible unless you sustain a commercial evolution that feeds investment in agriculture. Much as the Roman economy was complex and deep, it was still truly pre-modern given the absolute primacy agriculture and direct agricultural derivatives had in any degree of economic output or individual well-being.
It may help though if provinces are more self-administering in that there is a greater variety of commercial choices, and chances for legal developments advancing extended concepts in property, finance, and contracting.
How might more autonomous provinces handle law, anyways? Are we assuming that they copy-paste the Roman Republican system entirely, with the governor placed at the head as an appointed 'Emperor'? That would mean each province having popular assemblies. Even at this time, the Senate didn't actually create law of its own authority, it issued 'recommendations' that were ratified by a popular assembly, or enacted according to the power of decree of an existing official--like a consul, praetor, etc.
Personally, I'd consider it more interesting (and more helpful) if each province developed largely independently on actual constitutional structure. We know there will be a 'Senate' and the province's appointed governor will maintain the highest executive power, but each province could easily take a unique path to fill in the gaps. When Augustus or a successor has such a law regarding the provincial administration enacted, we could well see individual governors at the time exercising a very outsized influence on the process and precedent of each province's constitutional structure.
That depends though on the legal independence of the provinces, and their abilities to administer local courts and decisions thereof.
And outside Italy, no matter how widely Roman citizenship is spread, Romanness tends to be something on top of existing identities rather than transforming say, Egyptians into being fully Romanized - its more, one is a Roman because one is part of the empire, but that's it. Remove the empire and the sense of being Roman fades.
I don't think that's entirely fair, the upper classes in the West lost the Empire and made accommodations with the Germanic kingdoms now ruling them, but even then they lamented the uncultured environment and challenge of being isolated from "Romanness". Then you have weird stuff like the Romano-British, Domain of Soissons, etc. What it meant to be Roman also certainly had changed greatly from the time of Augustus, so it's not entirely an apples-to-apples comparison.
In the end though, Romanization seems deeper than a mere layering of identity, though doubtless that's how it began. How else could the Greeks have ended up adopting the mantle and titles of their conquerors to the point that being Roman was something natural and inherent to anyone "Greek" anyway? Or how Constantinople finally fell while still under the banner of SPQR.