The approach of the modern superpower is much more effective: decentralized power but overall alignment. There's no coincidence to America's approach. It isn't ideological. It's pragmatic.
1) Much of that expertise has come directly from US involvement. See: Western Europe, Japan, Korea.
2) Much of the other expertise developed specifically because of US non-involvement. See: the Soviet Union and the states it influenced and supported. There were even plans to attack/nuke the Soviets, who were the only real rival post-WW2.
https://en.wikipedia.org/wiki/Operation_Unthinkable
Had the U.S. wished to, it could have easily formed an imperial state following WW2. That would have been in-line with essentially every large state in human history. Thankfully, they didn't, and the world is better off for it.
The tools of modern warfare are too widespread and easy to adopt. You can’t do it anymore, the old school empire is just as dead as old school fortresses. Technology has broken it.
I have friends who served in Afghanistan. I’m not unfamiliar with how powerful the US military is. But even that power is too weak.
America’s approach is way more resilient and the control exerted is much easier to retain.
Every empire since the year dot captured land, with peasants farming it, who could be taxed, to pay the soldiers, to capture land... that was the business model. A little profit was left over to pay for cities, palaces, pyramids, etc.
This flow of money from country to towns was reversed by the industrial revolution. Within almost every country now, the cities are taxed to pay the rural voter base (or to pay off the rural might-be-revolutionaries, in places with less voting).
Not the only thing going on, of course -- changes in weapons matter to the balance, as mentioned. So does the rise of literacy & nationalism, which made the idea of rulers who are too distant (by ethnicity, language, or religion) from the population base (as they were in empires, almost by definition) into a rallying point. And thus raised the cost of holding land.
You're right that you can't hold an empire with only force, but I would argue that was just as true during the days of the Roman empire as it is today.
Sure, the Romans used (for the time) overwhelmingly advanced technology and amazingly brutal tactics to conquer Gaul and Britain, but they maintained their hold over those territories by culturally assimilating the native populations. Gallic and Britanic Romans spoke Latin, wore Roman dress, and even followed Roman sanitary customs -- there's a reason there's a town called Bath in southwestern England.
That culture continued to exert influence long after Rome fell as a central military power.
Imagine, for a moment, that each one of these had nukes. What's the probability they'd use them to make a point as an aggressor/opressor? Even risking MAD?
Also: MAD only exists if you let your opponents acquire nukes too.
Given everything, I think the highest likelihood outcome is that they behave similarly.