Xi has some crazy longevity genes I found out. His father died at 88, mother still lives at 98.
He is now only 71 years old. Probably at least 20+ more years to live with superior and modern healthcare.
No reason to appoint a successor and create a possible opposition to himself, and friction in general, now, if at all.
In my opinion, it's better to let nature take its course and allow the most capable one to replace him after his passing.
There will probably be some round of infighting when the most capable one will emerge as the new emperor then again.
But, by that time, the West would have long disintegrated and all external pressure eliminated.