the likely sucessor is Mus'ab.
depends on the pod assuming a late pod that Mus'ab listens to al-Ashtar and Mus'ab detain and hold the treasonous leaders hostage, releasing them on the condition of victory or executing them if defeated and says he wins the battle of Maskin even though he sustains so much casualties that an invasion of syria is not possible as al malik had attempted by now three times and failed to conquer iraq and given how he just defeated a revolt would mean Abd al-Malik would likely face some revolts as well, Mus'ab is also busy cleaning his house so to say so no side likely marches on eachother thinking they will march upon them soon, but both Abd al-Malik and to a lesser extend Mus'ab would be worried about the byzantines, on the one hand Abd al-Malik relinquised all claims of armenia and gave it to Justinian II despite it being controlled by Zubayr, on the other hand Justian II captured antioch in 680s as show of force who is to say Abd al-Malik does not fear that this would occur now unlike the first fitna were both sides agreed to come together if the byzantines invaded we saw none of that in the second one as Abd al-Malik essentially gave justinian armenia and iberia so that he could deal with the Zubayrids so by this point both sides especially the umayyads would not be against using the byzantines to their benefit.
I see a peace following in all frontiers for some years, maybe a decade, until 700, with likely Abd al-Malik being the aggressor and trying another take at conquering Iraq. By this point, Mus'ab likely had dealt with the problems in Iraq and would make an attempt at conquest harder, and it's not impossible, depending on how desperate Mus'ab's or his sucessor situation is, that he also gives up his claims to Armenia and Iberia in exchange for the Byzantines not attacking them as well. That would eliminate any reason for Justinian II wanting to side with the Umayaads and might even change Justinian II's mind if he remains neutral or attacks Syria.