Open bookings question

[OceanCruise]

We usually cruise 1-2 times per year in a suite and prefer booking on board for the low deposits and extra perks. We have some circumstances for which we are not sure if we will be able to cruise for awhile after this year. Does Celebrity still do open bookings for future cruises and, if so, what is the time frame that you have to pick an actual cruise? Also, what is the time frame for future cruise credit if I end up having to change that sailing? For example, if I book a cruise, say for for the end of 2021, can I transfer the onboard booking perks/future cruise credit once the new sailings come out for 2022 or early 2023? I realize there would likely be a $100 pp change fee so not sure if this plan is even worth it.