V1 support ended December 15th 2013.
So your statement is correct: V1 is not supported anymore.
Box gave everyone about 18 months from first announcement, including giving an extra couple months past the December date to any heavily used app to move off V1. We also made as much noise about it in developer communities (including Stack Overflow) as we felt was reasonable.
Communication included blog posts, emails to application owners, and mentions in events like BoxWorks and BoxDev.
Feel free to reach out to Box for help at api@box.com and they'll do what they can to guide you through converting your application. Most developers are able to convert in a few days.