That is why I do not want to neglect any potential ally. The more we have on our side the shorter and more successful a coup can be. We do not want a bloody civil war or to fail at deposing Mengsk.
This isn't me really disagreeing with you so much as using what you say as a launchpad, but...
Of course, what kind of allies we can make depends on what our plans are. More on this below.
Putting Valerian in charge is absolutely silly. There's literally no reason to do it except that blizzard has a hard-on for monarchies.
Well, it has the advantage of
simplicity. See...
Those of you familiar with CGPGrey's
Rules for Rulers, a cynical but in some ways insightful piece, may recognize what I'm about to say:
The secret to overthrowing a government and reshaping it to one's liking is to create a strong network of key supporters who will
back that new government. The reason revolutions are more difficult than coups (and much less common) is that a coup can usually integrate part of the existing power structure into itself, so part of your network is pre-built. In a revolution, you're creating effectively the entire new network over the dead bodies of the old network. This requires a very costly struggle and one requiring much more favorable conditions or more extensive preparation.
...
A coup that replaces Mengsk with Valerian requires no radical restructuring of the Terran Dominion. Duke and Warfield still run the military, Starke still runs the secret police, Horner still runs the Treasury. There's some risk to them that Valerian will seek to clean house or cherrypick his own loyalists. But the risk is if anything less than with Arcturus, because Valerian doesn't have as many delusions of grandeur and is capable of recognizing when it's better to avoid creating antagonism with a reign of terror, hopefully.
Thus, none of Arcturus' top-tier advisors have an incentive to
prevent a coup that replaces Arcturus with Valerian. The thing can be done fairly quickly, with a surgical strike. All that is really necessary is to:
1) Make the sales pitch to Valerian without him ratting us out to his father,
2) Arrange a way for Arcturus to be killed,
3) Arrange for the right tools in place to present Valerian as the new heir.
(1) is an unknown to me since I never actually played
Starcraft II but is presumably plausible, (2) is
relatively easy with collusion from Starke or de Santo, and (3) is easy-ish for Treasury with its far-reaching bureaucracy.
Arcturus falls down 100 flights of stairs onto a giant pile of dynamite, so sad. Crown placed on Valerian's head, which (looks up the thread) may or may not have cat ears on it. Everyone keeps doing the same jobs. The face on the coins changes. "The king is dead, long live the king." Life goes on, except for Arcturus' life in particular. Very simple.
...
By contrast, a more radical change to the system requires more struggles against the existing power structure. After all, a man like Starke or Duke would definitely be very worried about what a radically restructured government might mean for his own personal future. Neither their skill set nor their biography makes them well suited to life in a republic with government by the masses. Staring down the barrel of a war crimes tribunal or something like one, they may prefer their chances under Mengsk.
This means we have a lot more of a fight on our hands to impose the new government. We have fewer allies who have direct access to Mengsk's personal security in a way that would ease the initial decapitation strike. And we have much more risk that if we approach potential allies, they might sell us out as a 'dangerous radical' who is likely to pursue an action that will get them killed by the rebels later if not by Arcturus here and now.
...
From an abstract perspective, a republic is better and putting Valerian in charge is worse. But the risks of pursuing the former course of action are higher than the risks of pursuing the latter.