I can not speak for anyone else just me personally. Had I owned any .io domains that were being used for email or websites I would start redirecting to any of

I can not speak for anyone else just me personally. Had I owned any .io domains that were being used for email or websites I would start redirecting to any of my other domains and put an inline easy to read but attention getting banner at the top of the page that said something like, "Redirected from old domain to new domain be sure to bookmark" and I would link that to a news page explaining why I was taking that precaution and I would email my customers and communities with a short but sweet easy to read email explaining the same thing and would credit customers for their trouble so there is something in it for them. If it turned out to be a nothing-burger then I would use that .io for a blog page related to the community or something else non business or revenue critical and have links back to the new domain. I would keep the commercial content on the .com, the community forums on .net and philanthropic type content on .org or .io. i.e. news about donations to funding a new no-kill animal shelter and such