The best POD for this is Maurice remaining on the throne for a longer period, either by eliminating Phocas or by not forcing the army to winter north of the Danube.
Any point after this, the ERE is going to be screwed. Keep Phocas on the throne, and the Persians are still going to cause a lot of damage. They have the initiative, Phocas destabilized the regime pretty badly. Even if we have a son of his (the example of Priscus) as a competent Emperor, he'd have a lot of damage to repair.
Basically once Phocas comes into power and Chosrau II has an excuse to invade, it's all going to go to pot no matter who is at the helm. Chosrau II was kind of an idiot too, bankrupting his Empire to fight Rome when, in many ways, Rome was the source of his income in the first place. Persia and Rome, no matter how bad of enemies they were, did quite a lot of trading together. Destroying that economy with large scale invasions was a dumb idea to begin with. Maybe the guy was filled with dreams of Achaemenid glory, but whatever his reasons, it was unlikely Persia was ever going to hold on to those regions for any real length of time anyway.
I disagree, Giorgios, about Heraclius, by the way. I don't think it's his fault that events spiraled out of control. It's my opinion that he was the best the ERE had any right to expect during that era, and it'd be very unlikely anyone could have done much better, short of some sort of military genius like Belisarius or Narses suddenly showing up and miraculously driving off the Arabs.
Fact is, even if Phocas never came to power, the ERE might still have lost Egypt, Syria and Palestine. The religious controversy was tearing the Empire apart longer before the Persians or even the Arabs showed up. The fact that every Christian sect thought they could and should force their opinion on everyone else was ultimately self destructive, destroying the syncretism that made the Roman Empire possible in the first place.