I noticed a sudden trend in my GA starting on March 20th. I thought it was a fluke, until I noticed that 3 days later the change in numbers still persists.
All signs point to Google Analytics blocking an IP range and/or bots from being tracked.
Starting on March 20th, the number of pageviews and unique visits had a sudden drop. This also coincided with an increase of pages per visit (shown below).

I have compared my pageview data to Clicky and AdSense and their data shows no change. This leads me to only one conclusion: GA is blocking some type of traffic and has not announced this yet.
Did you discover similar findings? Let me know.