My headcanon is that the Matoran and Agori are living in New Atero with the Glatorian and Toa serving as a protection against the Skrall/Baterra/Rahi/Skakdi (well, pretty much everything else, I guess). The Ta-Koro Guard and similar Matoran organizations act as an internal police force while the rest of the Matoran integrate into society wherever they're useful, like Vo-Matoran working to provide the city with power, Ga-, Onu- and Ko-Matoran sharing knowledge, Ba-Matoran farming and Po-Matoran becoming architects.