Are those 15 minutes representative? That seems pretty high if so.

During California working hours it might actually be a bit low honestly as you would see several revisions uploaded for code review per commit and there are on average 200-250 commits submitted daily to the primary fuchsia repo.

The two biggest factors are how committed to this is Google and who is interested in developing and using this if Google drops it.

What do you think the answers to those are?

Factors for what? Deciding whether it's in life support? Deciding if it's okay for you to depend on it?