The 20650 battery from LG is now available, at least in the USA.
LG HG6, 30A, 3000mAh
https://www.imrbatteries.com/lg-hg6-20650-3000mah-30a-battery/
Yeah I noticed that, no 3rd party tests or easily searchable datasheets for them yet so I wonder how it compares to the Sanyo cells, probably has better discharge properties though considering most Sanyo cells are budget cells with meh performance and high discharge LG cells are generally pretty good. Maybe I can squeeze an amp or two more out of them into a Storm of Ra, at least until the 30Ts come out. Not that there is any reason to do that, OK yeah I may have a problem with building lights that push high discharge battery tech, but all these new cells have gotten me excited to see what crazy pocket nukes can be built, pushing hand warmers that also happen to emit light to the limit!
Waited more than 3 weeks for FT to ship the INR21700-48G. So I cancelled the buy.
Then I found it in a small brick-and-mortar vape shop in Hilversum, 12 ml from home.
And here it is, and going into the Warsun whose body I reamed to 21.4mm.
There is also a Sanyo NCR20650A available. 30A and 3100mAh.
I might have built the first dedicated 21700 flashlight. The Samsung 48G works great!
Here is a test of the HG6, by Mooch:
The new 21700 Samsung 40T cell has been tested by Mooch:
https://www.e-cigarette-forum.com/threads/bench-test-results-samsung-40t-21700…a-great-30a-3900mah-battery-better-than-ncr20700a.842165/
Looks good. 
Supposedly in the Samsung pipeline is a “mid-power” (10-15A ??) INR21700-53G cell, with 5300mAh capacity.
The INR21700-40T should be very popular for power tool battery packs. But how many non-custom flashlights on the market need a 30A battery?
The INR21700-48G is being used by Luna Cycle in a battery pack for one of their e-bikes.
been using the inr21700-30t in my versapak builds.
so far these are unbeatable in the high demand tools.
edit
30t!
33J ? Or 33G ?
30t
Fasttech just listed a BAsen 21700 at 7,58$ :
Bad cell, don’t buy:
Probably economy of scale. To get “volume pricing” on 1M units, a car that takes 500 more-or-less standard cells means getting there in 2,000 cars, whereas with a car that takes, say, 5 Übercells, you’d need to sell 200,000 cars.
(Dunno what Apple cells you’re referring to, so have to use my imagination…)
It is not merely a matter of pushing all the empty space out. That would be nice if it is only a backup storage unit.
It has to be charged and discharged often. That involves (a lot of) heat. So there has to be space, for cooling.
The “old” packs are air-cooled, The newest ones are liquid cooled.
I’m not very familiar with Apple’s electric car, but I haven’t seen anything indicating they’ll be using one big cell instead of many cells like everyone else.
I have had several macbook pro batteries in my hand and also the newer, glued-in variant. The ones I have seen dissected have multiple cells (battery packs) inside the battery. I am not referring to the new, split battery cell design in general, but the content inside the battery. The charge controller is typically on the motherboard and there is another chip on or near the connector where all the temp sensors are (Macbooks behave differently depending on whether battery is plugged in or not).
One of my older Macbook Pros had a “pregnant” battery (bulged out/non-charging) and actually fell apart. There were 3 packs inside, glued together with what I believe was Kapton tape. The individual packs looked like LiPo packs.
edit: the iPhone X battery also seems to have multiple cells
From an engineering standpoint it would be easier to protect future design changes with a flexible, multi-cell battery rather than a 1-battery pack that would have to be re-designed as well. plus all the efficiency/cooling/security aspects mentioned earlier. Imagine a huge, single cell blowing during a crash vs. very few cells in a multi-cell pack.
Phones and high end laptops use LiPO packs instead of cylindrical lithium ion cells.
They are the same thing just in a different shape.
Why tesla uses individual cells instead of lipo packs I’m not sure, it may have to do with cooling since they have to run fluid in between all the cells.
Also one other difference I’ve noticed between cylindrical and lipo cells is that you pretty much never see a cylindrical cell bloat up.
This probably has to do with the fact that it is wrapped in a spiral and sort of holds itself together tightly inside a metal housing.
Just about every other EV manufacturer uses prismatic cells stacked next to each other.
Telsa have pretty much gone their own route for much of the powetrain.
Nissan use a chemistry that is not prone to thermal runaway. LEAF relies on convection cooling and software ramp-downs to keep the battery in safe operating zones. It is less expensive but not as energy dense as what Tesla have been using.
BMW i3 also uses prismatic cells but has some active thermal management.
Google image search will find photos of dissambled BMW, Nissan and Renault packs.
There are also YouTube videos of BMW packs on the assembly line.