Your mention of Google's constant "toe-in-the-water" technique is a very interesting point, and is probably the biggest reason this will never happen.

It's really true how non-committal Google is with various projects, and like a research lab (not unlike the backgrounds of those who work there), they are constantly testing various proof-of-concepts to see which ones will bite. Other than search and their foray into geo, Google seems to keep playing an exploratory game where they know the desired outcome but not entirely how to get there. And they're in a great position to develop expensive proof-of-concept projects to see which gets them closer to their goals. Street View is an example of one that worked out handily but easily could have been cancelled in an alternate world; Wave unfortunately didn't make it.

It's this flat, "try everything independently" structure (with funding from some massive revenue) that makes Google a very unique and interesting company.