Romanity enjoyed a high status of sorts IOTL even. You don`t have to change THAT much...Well, how could we reach a state where it is like China, collapsing and reforming? How would the people of the Mediterranean accept this mantle of 'Roman' and try and restore the Roman Empire.
Higher levels of technological development mean either higher population density, or higher standards of living. In the case of the former, you have more military power, in the case of the latter, more civic support. Both are good bases for generals going for reunification (it´s not as if we didn`t have such unifier figures IOTL, too, only they never succeeded too much, and their statecraft was really crappy compared to what a resilient bureaucracy could bring you).