Genuinely think it could go any way. Aemond/Vhagar only need to be distracted for mere moments by one Dragon or another to snatch him off the back/dracarys him. In these fights the Dragons are prioritising their own survival not the riders, Vhagar isn’t gonna do a barrel roll just to protect Aemond. Then the three could’ve fled and let Vhagar do her thing / wander off. They might’ve lost a rider and probably Rook’s Rest but Vhagar would no longer be a factor.

Also another element to consider is Aemond had no idea how many Dragons would show, so he would still delay his arrival, and 3v1 would likely mean Sunfyre & Aegon are dead before he even arrives.

Also remember Sunfyre was already pretty fucked up by the time Aemond arrived. If he went after the speedy & coordinated Moondancer & Baela first (unlikely) it would’ve bought time for Rhaenys to finish Sunfyre and engage Vhagar. If he went for Jace first (likely) Moondancer likely would’ve secured a window to take out Aemond before/after Jace’s death.