Low-end microcontrollers are approaching PCIe-era signaling
The RP2350’s HSTX peripheral already reaches hundreds of megabits per second, making PCIe-class interfaces on cheap microcontrollers plausible within a decade
The RP2350 has 300 Mb/s transmit capabilities via its HSTX peripheral, and I wouldn't be surprised if 500 Mb/s opens up if they officially validate a 250 MHz overclock. On current trends, I suspect low-end microcontrollers will have PCIe ge