The number of grad students who want to stay in academia is dropping because dramatically better salaries and work/life balance compared in industry
Although this trend makes my life harder (since it is very hard to recruit good postdocs), i see it as generally positive. We need to be thinking about new sustainable models for conducting research in academia - and this "tipping point" will force us to grapple with this.
@barefootstache I think industry sponsored postdocs is definitely one way mechanism that might be sustainable.