As it concerns changes caused to India by the success of Rome, Muslim invasions are butterflied away, which have been a powerful element of disunity. ITTL Rome/*Byzantium does not absorb Persia, and so does not come to loom menacingly on the Indus, which may drive the Indians to unity. There is still going to be a helluva lot of trade contacts and penetration between Rome/*Byzantium and India, but I'm unsure of their net effect. As it concerns China, I'm fairly sure that in most cases a surviving Rome and Imperial China are going to be driven by ongoing cultural exchanges, trade links, and budding imperial rivalry into a millennial parallel rise into global superpower status. Theoretically the same might happen to India, if it avoids becoming a contested (and likely fragmented) buffer zone, or a Roman Raj.