Thanks, Henk.
21-70 it is. With initial production due to begin by year's end, I doubt Tesla will back away from that size.
For carry in a pants pocket, 1x18650 is a tad larger than I typically prefer. Even the diameter of the ZebraLight SC62w is a tiny bit bigger than I like. In a coat pocket, of course, 1x18650 is fine.
In the hand, I think I would like 1x21-70 better than 1x18650. In a jacket pocket, the difference does not matter.
I say, bring on the 21-70. Even if it were to dominate the flashlight world, it should still be possible to get 18650 batteries for a long time to come. There should be no hurry, therefore, to sell the 18650 flashlights I currently own.