What does this mean?
If you are a current version Autodesk customer with Autodesk Maintenance Subscription and continue with your renewals, you will receive version upgrades when they are made available. You will maintain the perpetual licenses that you previously purchased.
If you require additional perpetual licenses, as you intend to take on additional employees etc. you have until 31st January 2016 to purchase these licenses with recommended Autodesk Maintenance Subscription. From 1st February 2016, if your required Autodesk product or suite has a 'Desktop' equivalent then your only option will be to subscribe to Autodesk Desktop Subscription (rental) for further licenses.