Roman Empire could take over Germania,Scandinavia and even Western Reaches of Russia and make it just as developed by taking in all the Germanic,Celtic and Balto-Slavic peoples and giving Roman and Greek culture aspects to them too. This could help.
The Romans could establish a satellite empire in India,Central Asia and Xinjang like how Kushans came in from Tarim Basin and did. Only difference would be that these come from Europe. Tocharians,Eastern Iranians,Indians are again given touch of Roman civilization so that they will be Rome's insurance if things go bad like Arab invasions,Hunnic invasions,etc. Large Romanized settlements will be then built in India,China and Central Asia.
Remotely possible scenario: Romans conquer entire Africa and use industrial level technologies invented by them and the Greeks, settle in it,Terraforming it,breed more and more in it and eventually Romanizing or Italizing it.