We've been at CP last breakfast seating a few times, and have stayed fairly long to where they had one of the buffet sides switched over to lunch but kept the other as breakfast. And even though I've read of people getting lunch items, we never have - the food was plastic-covered and they didn't have serving utensils out for the lunch side.
They will not shoo you out. We actually always try to get as late an ADR as possible for CP breakfast. We use this as a brunch to fill us up for the day. We get to MK for rope drop do some of the big rides, collect some FP's for after breakfast and then go to CP to eat. Works out great for us!
I just called and asked about the CP breakfast hours today - the CM told me that breakfast is served until 11. Of course I take everything a CM tells me with a grain of salt, but looks like you'll have a good amount of time!