The size limitation mentioned, 56x40x23cm (22.05"x15.75"x9.06") would not affect very many of today's travelers. It is actually larger then virtually all US and international airlines with the exception of Southwest, Spirit, and British Air (18" wide). It's close to the regulation size for American, Delta, and United, 22"x14"x9", except going from 55cm long (21.6", most European airlines' max) to 56cm avoids the problem of US 22" long luggage not meeting European limitations. Any luggage that meet US and European size limits would fit in the "new" limit.
If you are currently using carry-on luggage that exceed airline limits by a lot, and you've been getting by with it, AND if the airlines do start checking, you probably aren't going to get away with it anymore.
I use an eTech Weekender Jr. at 19"x13¾"x9" (48x35x23cm), and it's only partially filled and squishable, so I wouldn't be shopping for new luggage.