In my politician rework suggestion, I included some buffs for revolutions for the Age 4 Politicians.
The Cavalry Marshal, King’s Musketeer, and War Minister could all enable the Imperial upgrades to be available in the Industrial Age for the units they send. That would let you have at least one Imperial level unit after a revolution.
The Viceroy could enable some Capitol upgrades at the Town Center in the Industrial Age. Immigration (faster training time and population space) and Legendary Native Warriors (many revolutions have lots of native shipments) would make sense and be very useful upgrades after a revolt.
As for extra Age 5 benefits, I think if anything like a University building is added, some of the Capitol upgrades would need to be nerfed to compensate.