Charging via USB adds extra complexity and there is nothing wrong with the existing system, so I don't think it will have as much adoption as you predict. OEMs rely on manufacturers like TI to provide ICs and reference designs, and for the moment it doesn't look like there's a highly-integrated solution for USB-PD.
> and there is nothing wrong with the existing system
Yes, there is: it causes massive electronic waste because of incompatible chargers. Expect the new EU regulation that covers phones etc. (that replaced "voluntary" measures) to be expanded to cover laptops too, or at least for manufacturers to get threatened with changes to th regulation, if manufacturers don't voluntarily switch to USB once suitable chargers start being widely available.
There is nothing electrically wrong, and while I agree that there have been many different connectors used and having one standard would be great, manufacturers do tend to settle on one of relatively few standard connectors (the majority being barrel plugs of various sizes.)
However, the solution is not a grossly overcomplicated standard like USB. It is a 20V barrel plug. Maybe if you want to get really fancy, include a resistor on a third pin for wattage encoding. Standardise on that instead - or pick an existing size - there are enough to choose from already ( http://en.wikipedia.org/wiki/Coaxial_power_connector#Standar... ).
This is a somewhat uninspiring attitude. There was nothing wrong with the PS/2 mouse and keyboard plugs either, nor the 25-pin printer plugs, nor some barrel plug for charging phones. But the problem is there were so many different things that all needed their own plug. Now there's no mouse plug or phone plug or printer plug since they all use USB. Laptops with a standard non-USB plug will still add to the duplication and inconvenience just like those old keyboards did. You won't be able to charge your phone with your standard barrel plug laptop charger, so you'll still have to carry two adapters when you travel.
There was nothing wrong with the PS/2 mouse and keyboard plugs either, nor the 25-pin printer plugs, nor some barrel plug for charging phones.
With the exception of the phone charging example, I would agree. The PS/2 protocol is vastly less complex than USB, and parallel ports are so simple they can be used as GPIOs with ultra-low guaranteed latency. Phones migrated to USB because they already needed the bulk data transfer capability along with power, and USB made for a good fit.
You won't be able to charge your phone with your standard barrel plug laptop charger, so you'll still have to carry two adapters when you travel.
The Dart has both USB and a barrel plug, which is the same as many other aftermarket adapters. (They could've made this more obvious in the marketing material, e.g. by showing USB devices plugged into it and not just laptops most of the time.)
I'll choose a laptop with a big robust barrel plug, and one that can be powered from anything outputting 12-24VDC, over one with a USB socket and requiring complex negotiation protocols to even start consuming power. It's the KISS principle. Standards that try to do everything don't tend to do any one thing particularly well, and introduce unnecessary complexity.
You don't need to implement full USB for USB power delivery. USB's data transmission is not used in it at all.
Detection of power delivery plugs is mechanical for standard A connectors (their male standard-A connectors are 1.3 mm longer so they could be inserted deeper in female power delivery connectors than conventional connectors so metallic shield connects detection pins) and based on detecting resistors and capacitors between ID pin and ground and power pins for other connectors.
For voltage negotiation new simplified bus and protocol was invented; it uses high frequency transmission on the same pin as power.
