In the world as it is today, the only way that is going to happen is if someone like Facebook or Google sponsors a decentralised solution. Projects like Matrix/Riot are technically great, but that alone is not going to make regular people adopt it. They want something that's easy to use and where most of their friends are. Don't get me wrong, I'd love to see a free (from corporate control) and decentralised chat platform gain as much adoption as email in the next decade, but realistically I can't see that happening.