The next doubling in capacity will likely come about through 3D NAND which allows for much larger feature sizes than current planar NAND. Samsung already have 3D NAND on the market (in 128Gb / die capacity), and other manufacturers intend to go down this route too.

Using larger form factors like 3.5" or 5.25" can possibly help.

You can fit 403 MicroSD cards into the volume of a standard (9.5mm) 2.5" laptop hard drive. The largest MicroSD currently on the market is 128gb, meaning you can fit 51.5 TB of MicroSD cards into a 2.5" drive.

SSDs need additional circuitry, chips and memory, but MicroSD cards aren't 100% flash either. This shows that the ceiling is very high even with current lithography.

My guess is that there's just not much market for a $200k+, 50 TB 2.5" drive, but it would be possible to make in high volume production.

If you need storage capacity, traditional hard drives will easily beat it in terms of TCO.

If you need IOPS, it's much better to use an array of smaller high performance drives.

I could picture it being useful in some military and space exploration applications but that's about all.

That suggests an interesting alternative path: WORM style flash, where you simply keep on adding at the end.

In fact today the main problem with the 2.5" form factor is being limited to the performance of SATA controllers, not how much you can pack into the space.

There's little reason to pay a massive premium for huge SSDs if your controllers limits you to a small percentage of the potential capacity of the drive. So instead you get things like the PCIe cards with 4+ controllers that gets RAID'ed together by the drivers.

As the controller bandwidth catches up, I'm sure that'll change.

>space exploration applications

Doubful, since they are not radiation hardened.

I could rather see a market for smaller size SSDs which contain lots and lots of chips and thereby have their own RAID subsystems.

radiation poses problems, but it has been since found that the radiation hardening measures taken on past IBM chips have been largely overkill for the application.

one can get near the same performance for much cheaper by using consumer electronics with redundant systems and a voting mechanism between systems.