I'm rather sceptical that this can work as a good alternative to Wikipedia. Wikipedia's content moderation system is in my opinion both its greatest strength and its greatest weakness. To create a better Wikipedia, you would have to somehow innovate in that regard. I don't think federation helps in any way with this problem.
I do though see potential in Ibis for niche wikis which are currently mostly hosted on fandom.org. If you could create distinct wiki's for different topics and allow them to interconnect when it makes sense, Ibis might have a chance there.