Tough situation Flying Sarah!
From the sounds of it, there will be no intakes until at least mid-2004. No/minimal expansion (perhaps even contraction?) combined with overstaffing and the general state of the industry would lead me to think that mid-2004 seems pretty conservative for any considerable intake.
On a brighter note... the teaching opportunity sounds excellent! I am currently studying primary education at uni, and being in front of a class is such a buzz! I don't know how the airlines view teaching (hopefully favourably for me when i finally finish my degree and apply to one) but the experience of living in another culture for a year has got to be considered a plus!
Check the contract to see if you can break it early. If you can, go for it! If QANTAS call, you can accept the offer. If they don't, well, at least you won't feel like you've wasted the last 18 months sitting by the phone waiting for *that* call from QANTAS.