“Certainly the Saudis and Egypt are not happy with current events. Who might they decide to support if Iran and Pakistan have at it?”
The Saudis have a long and deep security partnership with Pakistan, and a long and deep hostility with the Iranian regime.
The Pakistani nuclear program is often viewed as a joint program with the Saudis, where the Saudis paid a lot of the bills, and the Pakistanis are reportedly to provide weapons on short notice if Saudi needs them.
The Saudis paid a lot of the bills for the Anti-Soviet Mujahideen in Afghanistan in the 1980’s, which the Pakistanis trained and directed.
The Saudis have funded many extremist Mosques and Madrassas (religious schools) in Pakistan - notably big ones that produced the leadership of the Taliban.
Saudi Arabia in the past has rented whole Armored Brigades of the Pakistani Army to rotate for duty in Saudi Arabia itself, and provide security for sensitive facilities and missions, such as the construction of King Khalid Military City (KKMC), and in response to to Iranian-inspired terrorist attacks in Mecca.
Not only would Saudi Arabia undoubtedly side with Pakistan over Iran, but Pakistan may actually be putting pressure on Iran at the behest of/in support of Saudi Arabia, who have been at war against the Iranian-backed Houthis in recent years.
Thank you for this interesting conjecture and supporting information. A further fact of interest, Iran has no doubt never forgiven the Saudis for the botched Hajj a few years ago that ended by killing at least 400 Iranian clerics, not to mention thousands from other Muslim countries. I think the total was about 4,000 visitors, not counting home grown Saudi dead. Shows what heat and poor planning can do to an improperly guided crowd.