I have the "Unofficial guide to Walt Disney WOrld with kids 2014" and have been watching stuff on YouTube about the new RFID wristbands and FastPass+ (I will now call it FP+)
According to my book, FP+ will eventually replace FastPass but that seems a long way off. There are lots of rumours about what will happen but my book says FP+ will enable you to book rides/attractions 60 days in advance so you have to have either a Disney resort reservation number or an actual Disney Park ticket to do this.
Also in plans "we re told is a hard limit on the number of daily FP+ reservations you can have" the rumour is that each guest will be limited to between 2-4 passes per day depending on park and crowd conditions.
The reasoning is when 7 dwarves mine train ride opens Magic Kingdom will have 13 fastpass enabled attractions giving rides to 19,000 people per hour.
Assume 2/3 of that capacity is FP and the other 1/3 standby riders, over the course of a 12 hour day that's 152,000 FP spots.
About 49,000 people visit Magic Kingdom on an average day so each person can have 3 FP before all the spots are taken (are you still with me?) BUT if 75,000 people visit they would need to keep the park open for 18 hours to give everyone 3 FPs. Not possible.
Disney plans to up the number of rides that have FP from 30 to around 50. hey will also allow FP for character greetings and reserving best views for spots for fireworks etc.
Speculation is Disney will limit you to one FP+ per attraction per day ie if you want to ride Space Mountain twice, once will be FP+ the other stand in line.
Also, rumour is that depending on whether you stay in value/moderate/deluxe resort or off site may influence how many FP you can have for particular head liner attractions.
This is all from the book. So for a while it seems FP will run alongside FP+ but if you have FP+ you can't have FP. Phew, that was looooong.