Is there a theoretical speed limit to WiFi devices over the next 10 years?

Because of four recent practices,* it is difficult to predict an upper limit for future overall throughput:

1. Channel bonding
2. Beam steering (MIMO shaping and directing the antenna pattern)
3. Mesh Networking (i.e. subdividing a service area into micro-cells). Residential examples: Google WiFi, Netgear Orbi or TP-Link Deco
4. Ultra wideband or Ultra-high frequency: In 2017, both Netgear and Asus introduced routers with 802.11ad WiFi (‘WiFi AD’). Although it still not widely adopted, it adds a 60 GHz radio to the existing 2.4 and 5 GHz radios, supporting 7 Gbps network speed).

Note that none of these techniques demands a high output power per channel. They all use ‘tricks’ to achieve higher speeds. But the tricks are scaleable. There really is no upper limit to any of these techniques.

Mesh networks don’t increase overall bandwidth, but by reducing the signal power and service area (and having many more access points), there is more bandwidth available for each device.