Opponents of the leap-hour proposal call it a meaningless fig-leaf proposal. It will take many millenia to accumulate 30 minutes of drift. By that time any agreement made today will be irrelevant. They argue that we should just admit that UTC should be decoupled from having a precise relationship with earth rotation. The drift rate is only about 0.5 seconds per year. If it becomes necessary to have a re-adjustment it will be a long time in the future. They can handle it then with a special one time adjustment.
I don't understand why, but both the UK and China believe that preserving the one second precise relationship between earth rotation and time is more important than all the headaches that it causes for telecommunications and computer systems.
The FT predicts that the leap second will survive the next standards meeting. I hope not.