Apparently, the OS X Mavericks upgrade has eliminated the ability to sync or replace via USB cable calendar and contact data on iPhones and iPads. It would appear that Apple is mandating the use of iCloud even though many of us prefer or need the USB cable option. This article from Apple might be of interest.
It would seem that rather a lot of us are disappointed with Apple over this issue. For some of us, myself included, the nature of our calendar and contact data prohibits the use of iCloud or any other cloud service. And then there are the issues of privacy, personal choice, and loss of convenienice.
My best advice is that we continue to let Apple know that we are not happy with what appears to be an attempt to force our data into their iCloud while eliminating our choices for syncing. Personally, I have already advised my colleagues on campus to avoid the Mavericks and iTunes updates. And I am looking forward to reading the tech blogs as word of the sync changes and restrictions gets around.