The FCC notification is that SpaceX will focus on the configuration of 12000 generation 1 satellites that will work best with 30,000 generation 2 satellite. Previously, SpaceX was hedging its bets and had a second configuration but now SpaceX is confidently proceeding with generation 2 satellite plan.

SpaceX would start launching the generation 2 Starlink satellites on Falcon 9 Starship rockets. SpaceX has been launching 60 generation 1 Starlink satellites with each Falcon 9 rocket. The current Starship launch vehicle will be capable of deploying up to 400 Starlink satellites during a single launch which will enable SpaceX to build the constellation at a much faster rate to rapidly expand internet service coverage. SpaceX could stretch the Starship and add engines which would increase the payload to orbit from 100-150 tons up to 220 tons. The Starship will not be ready to launch Starlink satellites until 2023.

Any early Falcon 9 launches in 2022 will likely be test gen 2 satellites that will not be part of the main constellation. The letter to the FCC indicates that SpaceX will commit to Starship deployment of Gen 2.

SpaceX will transition to Gen2 satellites which will be larger and much faster.

SpaceX started launching v1.5 Starlink satellites with laser communication that will reduce latency to about 10-20 milliseconds versus 17 milliseconds for fiber. Space laser communication is 40% faster because of light speed in vacuum vs fiber. Anything over 3000 miles has less latency via Starlink. SpaceX will put up Gen2 satellite network with satellites 850-1000 kilogram with up to 80 gbps capacity per satellite versus 18 gbps in current version 1. ~30,000 satellite Starlink Gen2 constellation as proposed would have a total instantaneous bandwidth of at least 500 terabits per second (Tbps) over land (~1800 Tbps including ocean coverage). As of 2020, the total installed bandwidth of global internet infrastructure was estimated to be 600 Tbps.