I hope those new 820 G1 panels use LVDS rather than what seems to be a migration to eDP. If it's eDP then it's not feasible. While I'm OK with the stock panel it seems others desire IPS-like wide viewing angles. Unfortunately there's been no success retrofitting the X220/X230 IPS LVDS panels.
I hope that HP PSG manager does make a Haswell ZBook 12. It would be a relatively easy addition that fits in nicely with the new model designations. ZBooks buck the ultrabook trend where a chunkier chassis = more power, price and performance. 2570P was almost ZBook i7-quad spec to begin with. It's just missing the better panel, Haswell internals and higher price. That info raises the profile of our system considerably.
It's only our 12.5" HP 2570P and the now discontinued 13" Sony Z3 that can host a i7-quad in a small chassis. While the Z3 is technically impressive, I prefer the 2570P's durability, larger battery options, socketted CPU, expresscard slot, better warranty. All the while at a significantly lower ebay price.
experimental howto: fitting a '820 G1' backlit keyboard
It's pretty straightforward if the keyboard itself fits into the chassis insert correctly. There is an additional backlight ribbon cable that requires either 3.3V+GND or 5V+GND patch leads attached to an appropriate spot on the 2570P systemboard to power the backlight.
Here's an tutorial of how a backlit keyboard was retrofitted to an Acer 3820T by doing just this: Acer TimelineX 3820TG Backlit keyboard mod