It's a shame Zilog stopped making Z80s. Presumably this means you can't make one of these from new components any more. Perhaps someone could create a new iteration of the same idea.
Even if you made a version of this board with the footprint changed to the QFP eZ80, it probably wouldn't work because the eZ80 has different memory mapping and clocking differences.
The 80's/90's VeriFone Tranz 330 credit card terminal, which has a complete Z80 computer inside with DART, CTC and PIO chips, 32K RAM, and a socketed EPROM.
The Cidco Mailstation, which has a Z80, sizable monochrome LCD, and full-ish size keyboard, perfect to hack into a TRS-80 Model 100 style laptop.
You can pick up either on Ebay right now for ~$25
It will probably be a decade or longer until those sources start to dry up, but even at that the Z80 will never become as rare as say, a SID chip.