I am a little curious as to how the Australia switch went down. It can't have hurt, though, that the number of World Cup places on offer to OFC stayed the same. Oceania kept their 1/2 place and kicked out one of the two likely teams to earn it. As the most recent confederational cup competition shows, you can get a shock result when there's only one team you need to beat.
By way of contrast with CONCACAF, there's been a CFU side in the World Cup as recently as 2006, and the confederation as a whole gets 3.5 places. I think CFU would need a full place to get paid off until there's enough of a dry spell for them to think that a guaranteed half place is better than their current shot at more. To my mind, that's a non-starter, because there's no way the region's strength, on its merits, deserves more than 1/2 place. My ideal would be to merge NAFU and UNCAF with CONMEBOL, grant the combined federation 8 places, grant CFU 1/2 place to be played off with OFC (throwing a bit of a bone to both in that it's by far the easiest playoff opponent each could get), and work out AFC/CAF/UEFA amongst themselves. I'm just very skeptical that it would be politically workable right now. Plus, it would involve significant risk for both the U.S. and Mexico, who have a relatively secure route to qualification in CONCACAF.
Not to mention that, as much as I rail on the crooks in CONCACAF, the crooks in CONMEBOL (Teixeira, Leoz) aren't really any better.