Practical? I think on the older ships, where the kids club is a small room - yes. They could easily convert the space to something else. On the newest ships - probably not so much. In terms of would people sail - I think yes, on the smaller ships. On the newer ones - I don't think they could fill them up in the summer months. Now if you are also asking is there a market for adults only - yes, I believe there is, but not for the entire fleet. Do they NEED to switch to adults only? Probably not. I've never seen that many kids on X. I have no issues with kids being around if they are well behaved. I also have no issue with adults being around, if they are well behaved. I would not care to sail on Carnival for many reasons, which do not include the kids onboard. I think the very few kids I have ever encountered on Celebrity have been well behaved - I think the parents probably realized the facilities for kids were limited and knew their kids would still enjoy the cruise / what was offered and chose that ship anyway. Some kids are OK to read, play cards, listen to music on their phone/tablet and others need to have a surf pool, zip line, run whatever. Parents can choose a cruise line to suit their child's activity level. Most of these lines also have some adult spaces (casino, bars, so they can do "kid" things with their child, drop them at camp, and still have both family and adult time). Those that want a more "adult" atmosphere - avoid those ships with lots of facilities geared for kids. Should not be a big issue. There's something for everyone.