One month decline amidst competition may be a statistical artifact.
In December 2017, China Unicom fell from 77,503M to 76,539 broadband customers. That's still the third highest in the world, three times as much as Comcast.
Competition is a natural explanation. China Mobile has been adding ~3M/month for the last six months and 35M on the year. China Telecom added 660K in December and 10.4M for the year. China Telecom now has ~150M subs and China Mobile 113M. Nearly all (>90%) at CT & CM are on fiber all the way home.
China has > 800M LTE subscriptions, with many of the 200M 3G customers soon to migrate. LTE speeds are often 50-150 megabits. It's inevitable that some people will go wireless only; 5M have chosen wireless for convenience in Japan even though fiber was available. But China Mobile and China Telecom continue to grow rapidly.
China Unicom has been struggling and the government has required Alibaba, Tencent and Baidu to invest >$10B. They are expected to revitalize the company.
On the other hand, the drop could also be a side effect of an audit or some other temporary factor. AT&T once had a disastrous quarter in broadband figures. On closer examination, it turned out to be a bookkeeping problem. They hadn't been subtracting the customers who canceled service for more than a year and eventually had to come clean.
|Wireline Broadband Subscribers|
|Unit: Million||Wireline Broadband Subscribers||Net Increase for the Month||Cumulative Net Increase for the Year|
for the Month
for the Year