Microfabrication technology can enable extracellular neural recording electrodes with unprecedented wiring density, and the ability to benefit from continued CMOS technology scaling. A neural recording electrode consists of recording sites that sense electrical activity inside the brain, and wiring that routes these signals to neural amplifiers outside the brain. We here introduce a scalable circuit model for recording sites and signal routing, valid for different amplifier integration approaches. We define noise and cross-talk requirements, and analyze how future CMOS technology scaling will drive the ability to record from increasingly large number of sites in the mammalian brain. This analysis provides an important step in understanding how advances of MEMS and CMOS fabrication can be utilized in large-scale recording efforts of many thousands to possibly millions of neurons.