There is nothing new in this system. Every Year CCB follows the same rule,i.e, if you want to participate in further rounds, you must surrender seats allotted in ant prior round.
As far as cut-offs are concerned, NITs are expected to close at a higher rank, while cut-offs of pvt colleges are expected to lower down. This is mostly because of two reasons-
1)Pvt colleges have not been allowed to participate in CCB till the 5th round.
2)23 pvt colleges will join CCB in SPOT round. Likes of Amity Noida, Jaipur,Lukhnow were not in the CCB last year.