I’m not sure the Facebook adjustments are going to cut it. I’m sure they will adopt some of the better G+ features, but every time they make a change, their entrenched user base screams at them for months on end — which is happening again, as we speak, with the newsfeed adjustments.
Also, now that Google+ is open to the public, and obviously has no plans of going away, we will likely see them steadily gain traction against Facebook and Twitter. Google has had many flops in the past, while experimenting, but when they put their mind to something, and make it a focus of their product set, they do well, over time. Examples: Gmail, Google Chrome, Android.