This is the first I heard of ZeroCater as a bubble company, which I'm assuming is because they're dependent on tech companies whose bubble may burst. (Being in the UK, I don't know that much about them, so this is just an assumption.)
I think it would be shame if the model failed just because of fluctuations among tech startups. It should really apply to any business where people want to attract and retain talent.
Having benefited from this deal at Google, I feel like it has a lot of benefits for both the company and its employees.