[hkmurakami]

Big companies often have arbitrary guidelines such as "only billion dollar lines of businesses are worth having". In this case 100M users may have been the threshold where $1B/year in revenue from the product was realistic.

[kbenson]

It seems like a large number, but at Google's scale it might actually be rather small. Google is a large company, and each product is something that takes resources that could be better spent somewhere else. I don't expect Honda or Ford to keep around a car that only sells a few thousand a year, knowing that it requires continual work and refinement, space in their plants to build, space on the lots to sell, and a business strategy. I don't expect Google to act any differently.