My understanding is that H2S is toxic to nearly all plants and animals. Barring some massive technical leaps, I don't see how humanity survives in the worst-case scenario. H2S on the levels of the Great Dying takes millions of years to clear from the atmosphere. Rich humans living in domes would probably die of equipment failure long before the atmosphere became safe once again for human life.

The H2S in question is produced mainly by sulfate-reducing bacteria in the ocean, so targeting these microorganisms might be one way to stave off disaster. That would require massive bio-engineering on a scale never before seen in history.

Right now we're just crossing our fingers and hoping we can reduce carbon emissions and ocean warming fast enough, and that we don't trigger (or haven't already triggered) runaway warming feedback loops such as the clathrate gun hypothesis.