I think the consistency of service would go a long way as well. While it can be difficult to roll out the latest and greatest hard product across the entire fleet in a short period of time, if I know that I'm going to be well looked after every time, and that I'll start getting the new hard product next year, I doubt I would go to a competitor (especially if I have some levels of status).
And doing this is probably the cheapest way to improve the overall product. Having flown on 3K on quite a few occassions (I'm now based in SIN), I find the SIN-based crew to be highly consistent. While they are not going to bend over backwards to resolve your needs, I know that virtually every time I step onboard a 3K flight, I'll get consistently reasonably ok services, which, I would rate higher than some Y QF SIN-SYD/MEL flights I've taken in the past.
Of course, for J and F, higher levels of services are required, but if Jetstar Asia can get the basics right, surely, QF can do the same across their 4 cabins as well.