Floating atoll remediation of civilization's environmental footprint would, in addition to permanently rewilding agricultural lands and containing all urban population effluent (including CO2, CH4, N2O and CFC emissions) for 10 billion people at higher than US standard of living, sequester on the order of a teratonne of CO2 from the oceans and atmosphere.
The Seasteading Institute is being left behind by AT Design Office under contract to the Chinese construction firm CCCC, as they proceed with the pilot project to build a 10 square km floating city. What the Seasteading Institute has going for them is their association with Breakout Labs via Peter Thiel, as it supports fluid dynamics research for of the Atmospheric Vortex Engine. Although the AVE would be advantageous even with advanced nuclear technology, any radical reduction (less than 1 cent/kWh) in electric cost -- with or without the AVE -- will suffice to enable the rest of the floating atoll remediation. This is one of a few things that Marshall Savage didn't have the technical chops to address -- the other major things being photobioreactor technology and the notion of atolls unifying beachfront real estate demand with wave break for fragile (hence economic) PBRs.
At this point, it appears to be an entirely feasible economic proposition given the requisite lowering of cost for pollution free electric generation.
If the AVE experiments currently underway attest its economy, the Seasteading Institute can take the floating atoll proposal, package it up the way Mashall Savage should have, and present it to the Chinese. They'll bite.