Let's think about how people use the internet.
You need to look something up, find something. A reference picture of a cat. A house painter in DC. How AC/DC conversion works.
Right now, there are two ways to do this. Google search and Wikipedia. Google+ offers to radically enhance Google search: your connections and interactions in your Google+ network will validate you, so your travels carry much more authority than any astroturfer. Moreover, your connections will allow Google to guide you to exactly what you're looking for because your friends' friends' friends' already went there.
As for Wikipedia, I'm sure Google's coming up with an alternative. Probably +iPedia.
Oh, and some of you might use CraigsList for the more local stuff. Thanks!
News and Updates
I suppose a lot of users still go to, say, Wall Street Journal's or New York Post's site for news. Just browse on over at 9:30 AM and see what Murdoch wants you to know about.
However, a lot of us get our news via less restricted feeders. Things like Twitter, various filter sources such as Gawker, and thousands of specialty blogs that cover any kind of news you like.
You can argue that these don't have the gravitas of a major corporation with political aspirations, but that doesn't slow them down any. Already Google is a pretty important player here, not just passively through their search rankings, but actively through their news search, "top stories" section, and so on.
Not just news, of course, but also un-newsworthy things that matter to me, such as whether a friend's startup succeeds, or whether Germany is increasing or decreasing investment in solar power, or whether somebody's getting married. These also come to me through feeds, but mostly through different ones.
Google+ offers to take this and centralize it. Through Google+ circles and the I'm-absolutely-sure-it's-coming "extended circles", Google can easily aggregate posts and links and topics right to your Google+ page. It's probably similar to the iGoogle home in nature, but much more contextual and intelligent, so it can give you a wider variety of The News You Want without getting exposed to The News That Makes You Uncomfortable and still getting The Irrelevant Crap That Your Friends and Celebrities Like.
IE, Google+ is Twitter, Gawker, and Facebook all rolled into one, plus a few more things too.
Videos, TV, and Entertainment
A lot of people use the internet as a TV replacement. Just cruise over to Hulu.com and see what Murdoch wants you to watch. What, you didn't know News Corp has fingers in Hulu?
Let's go to YouTube instead. Oh, Google already owns YouTube.
Outside of actual hosting, most of your entertainment links come from filters and friends. These are the same sources that pass you news and updates, so the same things that will allow Google+ to dominate that arena will allow it to dominate this one.
A lot of people use the internet to go shopping. Buying books from Amazon, doodads from Etsy, shirts from Think Geek, and so on. Right now, a lot of us pop over to the store that we know carries what we want, and simply click "buy". The times we want a comparison on prices, we go to an aggregator site that trawls through a variety of stores, finds the pricing, and maybe rates them by reliability.
Google probably won't ever have warehouses full of shirts and books to sell you, but they do already have the "shopping search" which does all the rest. Combined with Google Checkout and, probably, a new service with a catchy name like "Google+ iNetCash Turbo", Google is perfectly capable of becoming the go-to for internet shopping, especially if they can break Amazon's grip on the books market by offering alternate sources.
Anyone who thinks Google+ is fighting Facebook is thinking way too small.
Hell, Google may even physically replace the internet, putting up fiber optics between Google-owned locations.
All of this is going to result in a much smoother, easier to use internet.
Owned by Google.