With the announcement of today's merger between Frontier and Spirit, there will now be Aussie's on E3s at the 5th largest airline in the US. That's pretty significant given where we've come from.
As an afterthought, I wouldn't be overly surprised if you see E3s go even further. With this merger, Spirit/Frontier becomes a pretty serious contender. The Aussies will be the only untouchables in terms of being poached by the big 4. Maybe one of the legacies will even out that playing field too.