Eh, it's probably part of what it's intended for, but private ownership of small arms is, at best, a minor factor in whether revolutions succeed. Having the majority of your own, or a foreign, military on your side, is much more important. Or, if your military sits it out, widespread private ownership of small arms isn't really that big a factor anyway.
... now, if you're an unpopular faction trying to take over, and the military sits it out, that's another matter. Then having guns is very useful. Or if you're trying to destabilize things with guerrilla tactics and terrorism so the government becomes unpopular and successful revolution is feasible.
TL;DR: "We need guns to protect us from tyranny" is a well-loved, but poorly-justified, case for the second amendment.
> Actually even this is not enough; there are so many countries that fulfill these criteria and are still terrible.
Relative deprivation drives revolt. Guarantee every Somali exactly $2,500—no more, no less—a year and 99.99% of the population will deify you. Do the same in the US—let's say it's even PPP adjusted—and you'll be dead inside a month, and they may make a national holiday to celebrate the wonderful event that was your assassination. I suppose very very slow changes might not have this effect, but I don't think the effects of climate change will be that slow.
> Why would those in power ever allow a change to a voting system which effectively maintains their existing power structure?
The "American revolution" itself was arguably better called a "war for independence" precisely because it had little effect on who was on top in American society—so, given that heritage, I'm going with "no, definitely not".