I think where Google could build momentum is to try to go for a private ecosystem where everything you store (photos, notes, etc.) would be private. The facebook opposite.

That would be a solid alternative to Apple's ecosystem and you would see the benefits of going from Facebook to Google.

Google has a much better chance of competing against Apple's photo/notes/cloud services than it would beating Facebook. Also I believe there is going to be a tendency in the next few years to move out of Facebook because of the social network effect people want to get out of.

Google would be the only solid candidate for anyone not wanting to jump into Apple's products.