There are plenty of open core alternatives that replicate the architecture and ISA. Many of these are cycle accurate. Some have been tape-out proven. Hobbyist retro-computing enthusiasts who wish to build a Z80 system still have options even once new old stock and recovered CPUs become scarce.

There are clones, and updated packages these days like the EZ80, but they're not the same and they don't have the easy-to-use DIL form-factor.

Still I've always loved the z80, since my first computer the ZX Spectrum. Even now I play with z80 assembly now and again (mostly for CP/M retro-use).