The bad thing about Mastodon is that you don't own your handle and your data unless you run your own instance.
Maybe it could have a crytographic addon where you own handle and data cryptographically and can move it to a new server as long as you keep a backup locally and the private key.
Maybe you could but there is something to be said for running your own instance of whatever platform you use to spread your thoughts. It is close to the last word in avoiding censorship as long as the network operators remain (or become in the case of AWS and probably some others) neutral. As to whether this is scalable... remains to be seen but for "normal" people with a few thousand "followers" at best it should work fine even on a single board computer like a Raspberry Pi. That same SBC could host your mail - using a smart host (which could be run as a service) to push mail to the world so as to avoid an avalanche of spam. While it is doing its thing anyway you may as well add whatever web-related thing you might want to put out for the world to see, or maybe not for the world but at least for family and friends. It can host media services, a VPN service, etc. In short, it can be a stepping stone towards a decentralised net - which I deem to be a good thing.
