My triumberate has four positions, one from each of four parties. President, Senate Adjudicator, House Adjudicator, and Undersecretary. Each voter can only vote for one party/ candidate. The one with the most votes becomes the President, the next the Senate Adjudicator, and so on until the fourth gets the Undersecretary slot. One party's power is limited because the most it can win is the presidency, and that by forfeiting control of the legislature.
My worry about this is that it essentially takes the power from the final public vote and transfers it to the party nominating committees. If each party nominates one candidate, if there are four parties in the race it means all of them are going to get one of the jobs. So all the vote decides is what order they go in. The nominating committee gets to decide who has a chance at the job and who doesn't, which is a much more powerful decision. So, instead of weakening the party system, you have actually strengthened it.
It does mean that maybe the Greens and the Libertarians or some other underdog party could finally get a spot at the table, but in the end who gets the spot is not decided by the voters, it's decided by the party. That's essentially how it is now, of course, but made worse by removing the meaningfulness of the public vote.
I do totally agree about needing a new constitutional convention, though. I would take it a step further. A new convention, a new constitution, every fifty years. Trying to reconcile centuries-old documents with the realities of the modern world is becoming more untenable every year, in all kinds of ways, but politically it is especially painful. If there was a new constitutional convention every fifty years, the government could be fluid, there could be adaptation and growth and experimentation, and there'd be a natural check against the buildup of corruption that occurs over time in long-term institutions. And fifty years means that most everybody would have a convention occur once during their adult life.
I would also put an expiration date on every single piece of legislation. Ten years, and the law expires. Better replace it, maybe change some parts that didn't work so well the last time. This solves many problems, but I've got two big ones particularly in mind: the massive and incomprehensible size of the federal statutes, and the amount of time legislators waste on frivolous bills about things that need no legislation. If every law expires in ten years, there will be a natural limit to the size of the federal lawbook, and there will be real, important laws expiring every year that need to be given serious debate and replaced or changed or eliminated. Lawmakers will have work to do, and no time for the nonsense they fight about now. Every ten years, the tax code has to be redone - think that'll make it more simple? Plus term limits for everybody - the people that wrote the law the last time won't be there when it comes back around the next.
The entire government, in structure, content, and personnel, would regularly roll over, and the issues it spent the most time working on would be the fundamental ones, pruning and building on the mistakes and achievements of the past, keeping the discussion focused on the nature and purpose of government itself and how to do it. Nobody gets a vise grip on power for long, and nobody gets to cruise by and make no important moves.
Right now, we have a government that cannot learn things. It can't adapt, because the effort required to adapt the huge institutions involved is too tremendous. A fluid government can learn, it can try new things and isn't tied to huge, immovable pillars of tradition.
So, anyway, the original point of the thread...
I think revolutions are an absolute necessity for progress. Institutions tend to get more corrupt and more inefficient the longer they continue, and it's important to turn them over once in a while just to keep things moving at all. Ideally, this would be a simple, bloodless, natural thing. But humans are suckers for tradition. People love tradition, they get attached to tradition, they will defend tradition with violence. So sometimes shaking up tradition includes violence.
Thinking of revolution as a concept rather than a movement, though - meaning, just the idea of fluidity, of things changing - I think it should be the first resort, rather than the last. If thine government offends thee, pluck it out. Or vote it out. Again, I come back to term limits and statute limits and such. Things need to roll over.
Now, armed revolution. That's a different ball of wax. Armed revolution should certainly be a last resort. A good solution to a problem never involves violence. But sometimes an acceptable one does. If all the good solutions fail, and the change must still be made... what solutions are acceptable?
I can't speak to the Arab Spring nations. I don't know the situations - I shamefully acknowledge my first-world privilege, being able to not know the troubles of less stable nations. So, I'll speak of the world I know - would any kind of revolution at all work in America? I don't know. America is not just tied to traditions and institutions, it's chained to them. None of the ideas I floated above are ever going to fly in this country as far as I can tell. I would love to have a new constitutional convention and a new beginning. I don't have much hope of that being accomplished in the near-distance, without major shifts in the nature of our relationship to our traditions.