That assumes that CS grads will look for work exclusively in a technology role. The skill set of a CS major is applicable to roles well outside programming. Management consulting and financial services for instance recruit CS and EE grads by the bucket load.
CS employment in startups may decrease in the event of a startup bust, but mature companies like Apple, Amazon, Microsoft, Google, IBM etc. aren't likely to drastically change their hiring patterns unless their own business have been materially impacted.
Oh sure, people will still hire programmers, but I expect conditions to worsen dramatically. The rockstar making a $100k+ salary in a $1000 chair on top-of-the-line hardware with free meals at the office experience is very much an artifact of the startup bubble. Mature tech companies offer that to stay competitive, but I expect we'll see a return to salaries closer to $50k in grey cubicle Pointy Haired Boss environments when the bubble bursts.
CS employment in startups may decrease in the event of a startup bust, but mature companies like Apple, Amazon, Microsoft, Google, IBM etc. aren't likely to drastically change their hiring patterns unless their own business have been materially impacted.