You're right, the USD wouldn't collapse just because the Swiss alone devalue their currency the same way the Fed has done to the dollar. It's when Korea and Japan and Australia and the EU and the UK and South Africa and Belgium and every other nation does the same to keep from being isolated in the markets they've become so integrated with; the lack of independence you pointed out. The Swiss move was brilliant, but won't change the trend towards currency devaluation.
As cypherdoc has mentioned, each intervention occurs in sequence - partially because each national entity has a different tolerance threshold (disparate monetary officials are forced to act), and because staggering provides maximum effect (two popular movies released at the same time will share the spotlight to some degree; released a month apart, they each garner the majority in turn).
With the US trying to escape its own debt grave by devaluing the currency, the world acting in aggregate to the same effect locks the former in - no change overall so equilibrium resumes, negating Fed efforts. If the Fed can maneuver and devalue fast enough, a window of opportunity develops from which the US can escape the debt burden before that option becomes completely impossible. Of course, if any sovereign defaults, it could trigger the final deflationary collapse; the US needs the system to hold together in order to save itself, but everyone will be worse off with a crash landing now that monetary inflation has begun.
China is in a dire situation financially right now (mostly among its own, not with foreign interests), but it also has been stockpiling assets. That will allow it to coast for a while, providing the precious commodity of time which so few others have any of. In addition, even though it will take a long time, internally it is capable of growing whereas the US can't even maintain itself. Being able to take care of issues in-house is always preferred over being subject to the whims of a foreign interest (EU/US debtors at the mercy of foreign creditors).
If any nation were to allow its currency to appreciate, it would come out the winner and probably hold reserve currency status should the base grow large enough. The problem is that it'd be an extremely difficult transition and individual citizens of any nation, especially those without an understanding of finance, can't be expected to understand such a move. It would appear as if the entire domestic economy imploded until internal dynamics kicked into gear - that could take months to years, by which time there would probably be a popular revolt. Catch-22.
Which currency won't matter (SDRs?). The consolidation of power you picked up on is key. Undermining that base of power is the way out - crypto-currencies make central banks irrelevant; it'll just take patience and persistence (and hopefully not too much actual blood in the streets).