Got a shock too when I just came across the news (rumour) here. Hopefully, it's not true.
Anyway,that article from Sina sports just posted this morning didn't mention anything specifically about Ma Jin, so I'd say no news is good news. The whole Sudirman squad has set off to Hainan island yesterday morning to begin training, with two notable absentees.
First, Lin Dan wasn't included in the team. From what I've read in another article as well
http://sports.qq.com/a/20130423/000512.htm, he's been taken out of the Sudirman Cup partly due to his shoulder injury sustained at the BAC last week and lack of form. Li Yongbo and the coaches, particularly Xia XZ, have communicated to Lin Dan to take a rest, recuperate and prepare for other upcoming tournaments and concentrate on gaining ranking points.
Second, Chen Long who has a slight shoulder discomfort from the BAC, is still at Beijing to recover from it before heading for Hainan three days later. The earlier report also mentioned that the injured Xu Chen who missed out on the BAC is back to training with the rest of the squad at Hainan; no wonder Xu Chen and Ma Jin didn't play at the BAC.
The other names listed in the CHN Sudirman squad include Du Pengyu ( no mention of Wang Zhengming in the report, strange), Wang Yihan, Li Xuerui, Wang Shixian, Cai Yun and Fu Haifeng, Liu Xiaolong and Qiu Zihan, Chai Biao and Hong Wei, Yu Yang and Wang Xiaoli, Tian Qing and Zhao Yunlei, Ma Jin who will partner Xu Chen, and Zhang Nan who will partner Zhao Yunlei.