Hello All,
Saw this on Darril Gibson's 
blog regarding update to Security+ exam. I feel a little more comfortable knowing I have until July 2018 to take SY0-401. Check the link for full details but I included an excerpt regarding the dates below.
[FONT="]When the SY0-501 exam goes live, can I still take the SY0-401 exam?[/FONT][FONT="]A. Yes. In the past, CompTIA has had an overlap period of several months. For example, if the SY0-501 exam goes live in October 2017, you will probably be able to still take the SY0-401 exam at least until New Year’s Eve in 2017.[/FONT][FONT="]Update: The SY0-501 exam will launch in October 2017. You will be able to still take the SY0-401 exam until July 2018.[/FONT]