CCTV 1 news just announced that Chen Xiaojiang (陈小江) has replaced Ma Xingrui (马兴瑞) as Xinjiang’s party secretary. Another “unprecedented” change in the job of a Politburo member (Ma) mid-term.
Given the importance of the region, the Xinjiang party secretary usually sits in the Politburo, though he does not necessarily take his seat there until the following Congress. (For instance Zhang Chunxian (张春贤) entered the Politburo in 2012, after having been placed in charge of Xinjiang in 2010). We can now plug Chen into our 21st Central Committee Politburo list (and there’s an outside chance he gets it at the 20th’s Fourth Plenum). But he’s already 63 years old; so, if the 67/68 rule holds, he’s only positioned for spending five years there.
Most recently, Chen has been working in the United Front system. Since January 2022, he’s been the senior deputy minister there, the de facto #2. Presumably he worked very happily with Shi Taifeng (石泰峰), who recently moved over to run the Party’s Organisation Department (中央组织部), the organ responsible for promotions and appointments (including, funnily enough, to places like Xinjiang). [1]Friends in the right places, and another sign that the boss trusts Shi.
Ma Xingriu, 65 years old, has not yet (officially) got another post. Given his career in the military-industrial system, there will be speculation about a potential fall.(The China Aerospace Science and Technology Corporation (CASC), where he worked, has suffered from a number of high profile cases.) If that comes to pass, he’d be the second Politburo member this term who’s fallen, after He Weidong (何卫东), though we’re still waiting for official confirmation of that. Alternatively Mr. Ma could show up in another job in Beijing. The clock is ticking…
[1] Chen has only spent three years at minister rank (thanks to being executive deputy at the United Front Department), and while the Xinjiang job top is also formally minister rank, it carries with it that Politburo member halo, so it’s definitely a promotion.
Not quite “unprecedented”. All Xinjiang’s party secretaries have been replaced in the middle of their Politburo terms since 2010.
And it's too early to plug Chen into the 21st Politburo list. According to the Chronicle of the Formation of the New Central Leadership of the Party after the 19th and 20th Party Congresses, all preparations began at the start of the respective Congress years. There's no way that Shi, after only three months in the Organization Department, managed to secure a Politburo seat for his UFWD colleague.
As you said, Chen has only spent three years at the minister rank. He's 63 years old and will be 65 in 2027, the retirement age for the minister rank. My guess is he will be a placeholder until 2027 with no official Politburo seat.
Finally, among all the things Xi cares about, precedents aren't one of them.