The .CN equivalents of these domains are in use.
4-character domains can be a viable option for startups without much funding because many of them can be acquired for less than $100. With a little bit of creativity, a decent Chinese brand can be created from its matching domain.
For January, Namebio reports 92 sale transactions of 4-character .com domains. The highest price is $7,000 (71ZW.com) and the lowest price $100 (TZW1.com and 12KK.com). (Note: Namebio only reports sales over $100 unless you have a premium account.) Here are some interesting domains with their .cn counterparts already developed.
EMC2.com sold for $3,451. It was only sold about one month ago for $7,788, meaning the value has dropped by more than half. EMC2.cn redirects to a Chinese page on DellTechnologies.com. Dell acquired EMC.
3D88.com sold for $572. 3D88.cn is a design and education site of audio devices such as headsets and ear buds. The title of the site is 金三维 (Jin San Wei) where Jin means gold and San Wei refers to 3D.
XLC8.com sold for $226. XLC8.cn is a Taiwan-based site selling dowsing rods which are divine devices to help locate ground water, buried metals, gemstones, oil, and many other materials. XLC is the acronym for Xun Long Che (寻龙尺, or 尋龍尺 in in traditional Chinese) which means dowsing rods.
JD85.com sold for $140. JD85.cn is a game site where JD may refer to the game title Jue Di Qiu Sheng (绝地求生). This domain does not seem to belong to the JD.com group, the 3rd largest internet company in the world according to Wikipedia.
There are two more observations. First, many of the Chinese site names do not seem to match their respective domains used. Examples are HH69.cn (insurance), GQ38.cn (recycling), and PP81.cn (news). Also, quite a few domains are used for betting, such as JS72 .cn, 11MC .cn, and 26BF .cn.