I came for the vegan comment however as it was already there, the biggest change I could see from mass adoption of the vegan ideals are that the population would have an across the world increase in empathy to not only animals but because they aren’t murdered as part of societal norms the empathy towards and the treatment of humans is likely to increase as well. This could theoretically lead to an increase in environmental action helping climate change but also help addressed a number of socialogical issues at the same time. We are a long way from this however in the uk veganism has increased 1567% in 10 years so with this rate of change it is possible.
They are ace! Extremophiles are so interesting. One of the most prolific species on the planet and they are being considered as a potential to help terraform planets such as Mars https://www.researchgate.net/publication/334603822_The_Lichen_Symbiosis_Lichen_Extremophiles_and_Survival_on_Mars