Interesting...
I see where they're going with this, but I hope they don't lose sight of the biggest USP of the Pi - the ability to tinker with hardware via GPIO on a cheap (throw-away) module. PCIe is hardly a hobbyist accessible interface, and by the time you've added M2 SSDs etc. and made this a (pretty decent, if still minimal) ARM PC, you're not going to want to be poking wires into it.
I'm sure they've run the numbers and know that a lego-kit PC is probably going to sell better than a souped-up microcontroller, but learning about the nuts and volts is something we seem to be losing out on these days </grumpy old man>