A merger might well make the strongest G5 conference in all sports. It makes a lot of sense to have a mega-western conference that's not vulnerable.
But there may be financial downsides to that. It would probably invalidate the exit fees of the departing teams -- Not the teams leaving MWWC for PAC, but the teams leaving PAC like UCLA, USC, etc. A merger might need to wait a few years.
But I really like the idea of a 2 division PAC/MWC. There are probalby discussions behind the scenes.