For most people who don't have status, they will still fly VA after this program change. The smaller number of SCs does not impact them at all, as long as the VA price is competitive most of the time.
For people with status via family pooling, they will most likely stay VA as QF (and others) doesn't even offer this feature.
For people with Gold without family pooling, they may start thinking about QF but chances are QF Gold is just as difficult if not more to attain.
For people with Platinum without family pooling, they now have Forever Gold to aim for, which previously they did not have. VA hope that those real Platinums will continue to fly VA with this carrot in front of them.
And for anyone on BFOD policy, most of them will end up staying with VA (except for a few people who will go at great lengths to fly QF, but VA won't chase them anyway).
So whilst there are disappointment all round, I don't think many people will leave VA.
The VA lounges will be less busy though with all those Elite status via family pooling and/or partner airlines disappear ......