Recent PCI-SIG work on and Chiplet-to-Chiplet extends the specification beyond PCB traces. The PCIe 7.0 specification anticipates lossy on-package channels with up to 50 dB attenuation, requiring advanced equalization (CTLE, DFE) and possibly die-to-die PHY adapters. The layered nature of PCIe allows reuse of the transaction and data link layers with different physical media—a key advantage over monolithic protocols.