Assuming he can somehow manage to balance the non-existent budget and still keep the military happy?
Honestly, things turn out better for the empire. It splits into east and west upon his death (iirc, Maurice's original idea of splitting the empire into fiefdoms for all of his sons seems to have petered out), because on some level I think Maurice knew the eastern empire could not hope to hold onto the west. Africa was fading in the face of Berber expansion and was nominally independant anyway, and Italy was a weight tied to the empire's leg. Having someone keep tabs on the west/leaving it to its demise while the eastern empire focused on the Sassanians and Slavs was probably the correct option.
As for the Sassanid war; doesn't happen. Despite everyone assuming he was a warmonger, Khosrau seems to have been content with the current state of affairs. Did he want Armenia back? Sure, who wouldn't, but I doubt he would have gone to war over it with Theodosius in charge. In fact, having a friendly junior emperor in charge of Iran's rival would probably be a good thing. Note that Khosrau did not go to war until he had a pretender to put on the throne, and his aims didn't seem to shift into Total War-style conquest until the Roman lines collapsed.
That's not to say you won't have more border wars with the Sassanid Empire down the line, but it'll be just that: more endless border war. The unique circumstances that led to the knock-down brawl in OTL just won't be there.
...For now, at least.