Earlier this week, App-V super-guru Tim Mangan published an article on BrianMadden.com confirming, warning and restating for the record that the End is Nigh for 4.6 support.
"If you are still running App-V 4.6, listen up. Maybe you wisely listened when I cautioned you to not immediately jump to App-V 5 when it was released two years ago. And again six months later when SP1 was released. But then maybe you didn’t take me seriously when Service Pack 2 came out and I said it was safe to start the switch to version 5. But how did you miss what I said when SP3 came out in November? So let me be very clear this time."
The end is Quite Nigh. In fact, Mainstream Support will end in about 5 months, on July 14th, 2015. The official dates from Microsoft are listed on their support page here.
If you need to start moving to App-V 5 you should read through Tim's article, where he outlines licensing considerations and other issues. For more tips and pointers on App-V you can read some of his other blogs here on FSLogix, or on his own blog, Confessions of a Guru.