
What if Isard released the Emperor's Plague?
In this scenario, Isard unleashes the Emperor's Plague instead of the Krytos Virus on Coruscant after blasting off in the Lusankya. The Emperor's Plague was the opposite of the Virus, killing only humans instead of aliens, and was deadlier than the Virus, to the point where even Palpatine was afraid to use it.
Had Isard released the Plague, I think key New Republic politicians like Mon Mothma and Leia Organa would be too ill to continue working along, with billions of Coruscant's people. Borsk Fey'lya would seize this opportunity to make a power grab for Chief of State while Admiral Ackbar would use his role ad the NR Supreme Commander to block his rival's attempts. The Provisional Council was also made up of alien Councilors, and other human politicians would be forced to step up as substitutes to help keep the NR together.
Rogue Squadron would still go after Isard to liberate Thyferra from her in order to get the Bacta needed to cure the Plague. But in this timeline, Wedge Antilles, Tycho Celchu, Corran Horn, and at least half of the Rogues would be out of commission thanks to being infected. Funnily enough, the future members of Wraith Squadron might actually be asked to fill in the missing roles in Rogue Squadron. Especially if it was Wedge himself who vouched for them and planned it as a contingency in case something ever happen to him.
This would see Rogue Squadron utilising the future Wraiths' unorthodox tactics, which means they might actually defeat Isard sooner than the Rogues did in the original timeline. If the Wraiths could defeat Zsinj, then they can handle Isard. Particularly since their commando tactics are a good foil for Isard's role as a spymaster.
While the Wraiths may be able to beat Isard, there's a fair chance their actions wind up destroying the Lusankya like they did with the Razor's Kiss. The Wraiths save Thyferra and get bacta, but at the cost of depriving the New Republic of a Super Star Destroyer.