For sure running k8s is difficult, I don't think anybody would disagree with me there, but of course you can buy GKE. I have to point out that GKE is the only decent k8s implementation, EKS and AKS are not real contenders. Digital Ocean will launch their service, I've seen it and it's good and I hope they do well. But in general you can't really expect the Kubernetes landscape to change much from what it is today, which is basically GKE good, everything else meh. Why? Kubernetes is not really a proven business model for cloud providers yet. It costs the cloud provider more to offer Kubernetes and it not significantly drawing more users in (and consuming more). The obvious example of this is AWS lack luster support and commitment to EKS. If there was a big business opportunity Amazon would be doing more. I have no concrete proof but ECS and Fargate stand to make much more money for Amazon (just a guess). So in general the argument that running on GKE isn't bad I don't think holds up because GKE is the only decent option. DO has yet to launch, but they can't really standup to GKE because you have to look at things holistically. Just running the cluster is like 10% of the whole solution. You need to then figure out how to do authentication, authorization, load balancing (built in service LB and ingress are not sufficient), monitoring, logging, and disaster recovery. Google has a product in each of these areas, but they have 100x more resources than DO. Basically nobody can (or is willing to) put the money into K8s like Google does and Google has yet to prove that their investment is worth it.
That's not to say I don't think Kubernetes will survive. I do think it will survive and it will be around for awhile. Because it's a good fit for enterprise right now. Not a good cloud provider business, not good for small dev shops, but good for enterprise.