Would be cool and technically possible, but I doubt it will happen.
Big Tech throwing millions into marketing and vendor lock-ins vs OpenSource projects that are decentralised and often running on donations and goodwill. That's a very touch battle to win, especially when most people care more about ease of use and amount of possible followers than about privacy and decentralisation.
Mastodon grew, but only took a tiny slice of Twitter and half of Mastodon are bots or people who crosspost to both. I expect the same to happen to Lemmy/Reddit, and any other SNS that goes this direction.
I'm content with a stable and active niche group of SNSs. Hopefully the open source and decentralisation aspects can prevent it from dying and going to the next SNS as the big ones tend to do. Which cóúld be as people can make newer applications that work with the old ones as long as it all runs on ActivityPup. I feel it's the most realistic way of thinking.
But maybe I'm just too pessimistic. Even the biggest people in tech stuggle to predict the future of it. So who knows.