It's a work in progress but might be helpful to someone!
K8s in my book tries to solve arbitrarily complex deployment problems. To do so, K8s overall accepts being a complex monster. You have to fully commit to use K8s, you have to put everything you have into K8s, and then K8s solves a staggering amount of problems.
Nomad is much simpler. A good way I've found to describe nomad is: Nomad+Consul+Vault is essentially a distributed initd/SystemD + cron + secured store. That's all. It's powerful, because there are no problems you can't solve by scheduling + discovering VMs, containers and applications. But it's at a more fundamental and lower level, and it requires more work to utilize well. It's also less of a jump compared to K8s, but some stuff more or less solved in K8s is not in Nomad, so far.
I strongly enjoy working with nomad and we see other operations teams grow interested, because nomad functions and handles similar to something like VMWare. Sure, containers are weird, but it can do VMs, and it's still similar. For example, for an ES cluster on hardware with grafana/kibana/2 logstashes running "somewhere on these hosts", nomad is very pleasant to use.
But I doubt nomad will be as hyped as K8s because e.g. you cannot throw a helmchart at it to create a postgres/patroni cluster on abstracted storage for a servide with a relational storage requirement, as the hyperabstracted way needs.
CSI support exists and is being enhanced, but you will still need a CSI provider, and e.g. the GlusterFS CSI provider got eaten by K8s and now you're stuck with S3 or running Ceph. And running Ceph is a ... thing. And for example, you'll have to run the nomad autoscaler besides it, and other orchestration and management systems around it that K8s has, or has integrations for. There's just a lot of edges to handle, if you could just buy hosted K8s.
The benefit is huge though - you can orchestrate VMs and processes in addition to containers
One company I worked with went managed, another one didn't. I think hashicorp stuff is too barebone in general. I noticed way less headaches with the managed solution and I would just host it with them.
In contrast, I feel comfortable running a k8s cluster for a smaller business of mine.
I know there are great terraform modules out there already, but i wonder if many of Hashicorp's products soon will be available as "managed" services as well, allowing people to try something new with less maintenance cost.