I think Knative (and the scale to zero in particular) are best suited for request/response or event-delivery workloads. So you wouldn't want to run (for example) memcache or mysql under knative. FaaS and (HTTP application) PaaS are both good matches.

I think it's an open question whether a PaaS like Google Dataflow is a good match or not. It will certainly require more planning, but I think it's doable.

Yeah but don't forget this is a higher abstraction on top of microservices. I think the big take away here is that if your app falls into the patten of 80% of modern apps (can't remember where is saw that number, don't quote me :) and is split properly you can have all your 'ops' part as configuration.