* Available for all browsers and comply all web standards.
* Available for all languages across all regions, with accessibility features.
* Promise not to "launch and shutdown in a few years".
* Imply a real future product.
But I'm guessing what Google wants to do is to just prove if "game streaming" is technically / financially viable for mass crowds based on their technology in hand. If not, maybe shelf and wait for a couple of years without dumping a lot of resources and drawing bad sentiment.
What requirements are you thinking which should be applied to such a "tech test"?