Interesting theory, URD, one division of QF Mainline would certainly make $ense.
However, IMHO going for a lower/cheaper base than Impulse would be a waste of time for QF - certainly from a long term/safety point of view. (Lets not forget that Impulse is infact a cheaper base than Virgin.) With substandard wages comes poor morale, poor services, and (god forbid) even poor standards with regards to safety. All of that spells jets dropping out of the sky; which = no pax, which = no profit AT ALL.
Sounds harsh, but it certainly could be a reality they would have to face.
Basically, they just couldnt go too cheap. In the end it would all come back to bite them on the bum. Not Rocket Science, just common sense. But, hey, I am not a GREEDY Board Member/Major Shareholder. So what would I know about what is good for the long term of the QF Business!