Right, and then in Classic you would use DoReferenceTransaction to process the future payments. The same functionality should be available in REST but with the use of billing agreements / billing plans, or possibly just the payments API alone. I'm still using the classic APIs myself because REST does not support features I use like Guest Checkout. With billing agreements that sort of thing won't matter because you can't use Guest Checkout with them, but also the simple fact that it's all quick and easy while REST is a big cumbersome and tough to follow right now.
The Classic APIs are labeled as deprecated because they are indeed trying to get people over to REST, but they aren't going away. There are way too many people heavily integrated into those systems. If you're more comfortable with it I'd recommend you just stick with it for now.
Again, though, the same functionality should be available in REST with some similar collection of calls. Hopefully somebody else can step in and give us a tip on that. A map of calls from Classic to REST to setup billing agreements and process reference transactions would be great.
Angell EYE - www.angelleye.com PayPal Partner and Certified Developer - Kudos are Greatly Appreciated!