It seems that, with local authority budget cuts, any 'successful'/ over-subscribed school would be almost reckless to not become an academy and risk having less funding by staying in. Changing status means they extract their share of the pot before it shrinks. So the actuaries on MN will take all of a nanosecond to figure this one...
Some would say that this just shifts all the school support on any issues they can't fix themselves to central government (who aren't quite used to supporting a sizeable constituency of this type) or possibly to a vacuum. However it also seems that whatever the motivation (hard times, inherent inclination, whatever) there is a tendency of late in HMG to push until it breaks, and then repair if needed; with experts/professionals now blatantly treated as shroud wavers when they tender advice and caution against some of the more interesting proposals.