Multiple websites have been reporting over the last few days that the Be Our Guest restaurant has become a Fastpass+ only option for lunch. It does not appear that this is true, however the Fastpass+ option is available for guests staying on site. Guests can make these reservations with a valid room reservation here:
Guests can still walk up and receive a return time, but it appears that between 12:00 PM and 2:30 PM will be reserved for Fastpass+ guests. The availability of a return time is contingent on the crowds that day. It still appears this system is very much in flux.