edge226, you are absolutely right, and I assure you you're grasp of these things is far beyond mine. The IT guy does know, but is narrowed in his purpose and missed my narrower one, now does, thinks it's interesting, and of limited mass market appeal = I agree. But, I'm on a different path.
First, as a mechanic on non-consumer non-street/highway machines I have a heavy interest in preserving obsolete methods of diagnosis and firmware programming. Things you may literally need out of production pieces not only to move forward, but simply maintain. This always requires specific hardware configurations. This means paravirtualization as the possibility. Previously I'd mention a pmcia interface..good luck on that! To my knowledge, hardware passthrough is not a docker feature, and if it is would be a major stumbling block to portability. I understand docker to be entirely software based, possibly answering similar problems. I take debian with qemu/kvm as the most viable foundation moving forward since so far it does the best job at reaching back in time with modern hardware.
Second, I'm more interested in an architecture like Qubes OS as a method of rolling up many requirements into a single machine, while fully exploiting modern core counts and memory capacity. With Docker I have a bias perhaps that is has a bloated nature and simply duplicates and compartmentalizes code again and again, each with specific tweaks for induvidual packages of purpose to be singular and portable. One could argue that fully exploits cheap storage, I'd silently agree, but to me it's still massive duplication of code, bloat.
Third is just that, bloat and duplication. I've worked hard to reduce to a common code base without needless duplication. While not so conducive to a rolling release model, I run a single base core that is read only with a package of programs on a few read only layers on top of that, then run-time rw layers representing each VM on top of that. So I don't know what the footprint of a docker image is to do a specific job, but I have VM's with <100MB footprint. Not exactly portable on a specific purpose level, but I can spit out an image to an ssd in minutes that will then boot some other computer in the functional form needed, like to a toughbook with a removable drive and the ports required. Also, theoretically, without specific knowledge of the architecture the base layers of the system are isolated, dare I say impervious to attack. With a tiny net install image and a 2.2 GB pool the system is reproducible off-line. Add to that a 1.4GB truly portable image of XP, that can also make an installable image.
So, docker for sure has a bright future. But for serial and parallel and omg pcmia equipment, no future at all, but I'll try to offer a bridge to the obsolete. The last tough book I built could talk to Bombardier, polaris, cummins, cat, and normal obd...that's an odd machine. I could imagine a breakout box and a single usb to a laptop, tablet or even a phone, with a docker like package to do these things, it's just not here yet