You should print everything, bury it and give the location to your close relatives. I’m only half joking. Analog security is something we should take more into account.

I've done contingency for my last two companies. It's pretty simple and straightforward.

• All user-input passwords should go in a password manager that allows you to share with someone else. I recommend 1Password, but I recently (on Tildes) have heard lots of good about Bitwarden. I haven't tried it yet though so YMMV.
• Route all accounts possible through a central account management system. I use GSuite for that; it's cheap and very standard, and most websites allow login-with-google (which gives you login-with-gsuite for free).
• For infrastructure, use the excellent Terraform. This allows you to define infrastructure relationships declaratively. It also avoids storing too much shit in your password managers and having to copy/paste those around, as you can use various providers to lug credentials around more securely (eg. to SSM, or gitlab variables, or what have you). There's even-more-secure solutions for this (such as Hashicorp Vault), but they're overkill for small projects.

This is some example terraform config for one of my projects:

// ssm
resource "aws_ssm_parameter" "overframe-db_user" {
	name = "/overframe/db_user"
	description = "Overframe database user"
	type = "String"
	value = "${aws_db_instance.overframe.username}"
}
resource "aws_ssm_parameter" "overframe-db_host" {
	name = "/overframe/db_host"
	description = "Overframe database address"
	type = "String"
	value = "${aws_db_instance.overframe.address}"
}
resource "aws_ssm_parameter" "overframe-db_port" {
	name = "/overframe/db_port"
	description = "Overframe database port"
	type = "String"
	value = "${aws_db_instance.overframe.port}"
}

// gitlab-ci
resource "gitlab_project_variable" "overframe-AWS_REGION" {
	project = "${gitlab_project.overframe.id}"
	key = "AWS_REGION"
	value = "${var.region}"
}
resource "gitlab_project_variable" "overframe-CLUSTER_NAME" {
	project = "${gitlab_project.overframe.id}"
	key = "CLUSTER_NAME"
	value = "${aws_ecs_cluster.overframe-fargate.name}"
}
resource "gitlab_project_variable" "overframe-REPOSITORY_URL" {
	project = "${gitlab_project.overframe.id}"
	key = "REPOSITORY_URL"
	value = "${aws_ecr_repository.overframe.repository_url}"
}

You can set up a dead-man-switch to automatically unlock your password manager (eg. by sending an email with some one-time-use credentials) for a trusted person if you want to get fancy, but I'm personally a proponent of "every serious project should always have at least two people with super-admin access", even if that role is the only role that second person fulfills.

(AMA on contingency if you like)

I'm personally happy with that answer.

The community can stand up and take over with a new chapter rather than someone being hostage of the/your original will. The community wouldn't be tempted so much to compare the successor to the predecessor since you didn't choose them to pursue your goal.

On the topic of data, I personally think the data should simply vanish. The problem with keeping that data open is that anyone who wishes to delete their data would find it much harder if anyone has access to the full database.

Furthermore, if someone's account were to be compromised which was in the original database, they'd be able to impersonate the person on any of the successor's services.

I don't think there'd be a safe avenue in which you could give tildes to someone else without it causing many issues really.

What you should do is that record a message that releases upon your death that you have hidden a master vault password for Tildes in five parts around the world and whoever can follow the clues and gathers all five pieces of the password becomes the new Deimos. You don't actually have to do any of that, but even if you just release the message and have no intention of setting up a post-mortem scavenger hunt, it would be kind of entertaining to watch it play out.

Weekend at Deimos'? This sounds like a gnarly sitcom.