Google is everywhere. Google is practically synonymous to Internet nowadays. Everyone wonders what will be Google's next move, and what else can they do to completely monopolize how we use the Internet. But I believe that perhaps they are getting to big to manage.
If Google keeps on diversifying as they have, they may lose their focus and deliver OK services, when up until now they have been great. Google's success depends much on its company culture, and if the company grows out of their hands, it will be very hard to maintain it on the long run.
Google's main challenge right now is managing its growth, I believe, and making sure that the next innovations they come up with are consistent with what they have delivered up until now. If they manage this correctly, I see the future very bright for them.