You are right that some apps will become popular and they will become part of centralized backbone. People using Mastodon or any other decentralized apps based

You are right that some apps will become popular and they will become part of centralized backbone. People using Mastodon or any other decentralized apps based on Kadmelia DHT and other technology will still be using Android, ios, Mac or Windows as primary base platform. Only very small subset of people will use Linux. So in the end, it will still be dependent on centralized infrastructure. It's not just about one or two apps but the overall internet architecture and its control and dependence on bigger company. Now as Apple, Google, Microsoft and Amazon lay their cables across oceans, acquire ISP's and telecom, will control from packet switching network to application delivery used by normal person.