This is a little vague to me, but seems as though he feels others will carry on:

In either case, I consider myself extremely lucky to have people that can manage the project in future, and can only imagine what it would be like for someone without that luxury. I can’t help shake the feeling that somewhere, the software I use is being developed solely by volunteers who would rather quit, but don’t have the ability to say “no”. This post has been delayed for that very reason, especially when so many people have given so much, and I feel they deserve a proper goodbye. At this point though, I can’t find the strength to leave on better terms.

And in case instances.invidio.us shuts down at the same time, here is a current list of instances:

• invidio.us
• invidious.snopyta.org
• yewtu.be
• invidious.tube
• invidious.13ad.de
• invidious.xyz
• invidious.site
• vid.mint.lgbt
• invidiou.site
• invidious.fdn.fr
• invidious.toot.koeln
• invidious.ggc-project.de