Hello Brittany,
Welcome to the Autodesk Community, and thank you for participating in Answer Day!
You are absolutely correct that any Perpetual Licenses you own, or purchase prior to the change on January 31st, 2016, will be permanently owned, and will function indefinitely. These perpetual licenses are sold for the current version of software (currently the 2016 release), but the license purchase alone would not automatically upgrade and allow access to the 2017 release when it comes out. For that benefit, we would also need to purchase Maintenance Subscription, which is an annual subscription that will unlock upgrades, technical support, and flexibility with accessing previous versions. If you've purchased this maintenance subscription, you will be able to continue renewing beyond the January 31st date.
Beyond this date, we will only be selling new licenses in the form of Desktop Subscription. While this will be the only license model available on February 1st, you can take advantage of this lease/rental model right already in our eStore or through one of our many Authorized Resellers. These subscriptions are very similar to the benefits received from Maintenance Subscription, with the added benefit that there is a lower, up-front cost, and you have greater flexibility assigning the software to various users through the User Management function. For a full breakdown of features and benefits, the following link does a great job of explaining the specifics:
Desktop Subscription FAQ
The "simplified subscription" would then be referring to your ability to re-assign your software's seat as needed. One user would be the Contract Manager, who can give permission for each user to access a program from their lineup, and can remove and change access as often as needed. With this flexibility you can take advantage of swapping active users, and save money on purchasing additional seats.
While most products can be purchased individually, Revit is part of a small collection of products that only comes in a product suite. The Autodesk Suites breaks this down with a little more clarity, and shows which suites contain this product. (A recent addition to this list is the Revit Collaboration Suite, which includes Revit, AutoCAD, and A360 Team)
Going forward, any additional seats purchased after January 31st, 2016, will need to be on the Desktop Subscription license model. These licenses can work in conjunction with your perpetual licenses, and would have it's own reference when you sign in to your Autodesk Account. There won't be any clash or issue adding this to your software portfolio, and can begin taking advantage of the added user management benefits right away.
I hope this helps! Please feel free to reply if there were any other questions or concerns. Until then, have a great rest of your day and try not to work too hard!