I think Google are pushing it hard and will force the hands of business owners to build content specifically for Google+ in turn making them push people to the platform.
We can't say it yet - but Google dominating over other Search Engines could probably be an advantage for them - with Facebook only a social network and not that as large as Google. As Google continue to innovate and change every now and then, even on clandestine acts that they do on their algo, there could be no final word yet if they are going to win over FB or not.
I don't think it will replace it but I think it will become big enough for businesses to need some sort of profile on there - it after all backed by Google
If the latest move to make Picnik available through Google+ goes ahead then all the teeny boppers (like my daughter) will use Google+ to edit their images and then publish them there. Could be a "master stroke" IMO