Yep, that's... interesting. For sure real time web application needs better reactivity when scaling up and down. But you can already achieve this kind of reaction time on existing platforms that uses Docker for example (disclaimer: I'm working on the Scalingo PaaS that already supports MeteorJS app, see https://scalingo.com/meteorjs-hosting).
I've also evaluated Heroku and the Ruppell's Sockets, so I can answer this from my point of view. The problem is that it's a workaround solution - all TCP traffic goes through an external server, which is unacceptable for any serious use case. How secure is that external server? What if it goes down? There isn't really anything that can be improved, other than Heroku natively supporting TCP sockets.
1. when we'll charge a credit card (which should happen in the coming weeks as we're incorporating the company), we'll be already cheaper than Heroku in a price/performance ratio
2. to be honest we're more pessimistic than you about the number of containers that we can host on a single server like the one you cited (at Appsdeck we use only SSD equipped servers with more cores than in the machine you cited)
That said, our price could change a little bit depending on the real workload that our cluster can handle in real life.
As a happy (small time) Hetzner customer, I concur, I don't think it's quite so rosy as parent hints at. The most crucial part: look at the bandwidth. Peek at 1Gbps (probably more like 5-600 after overhead), guaranteed 200 Mbps. If you divide that by 100, that's just 2Mbps guaranteed bandwidth per container! Sure, you can oversell, but then you're in a different game.
I was about to mention this. I know of at least two (very) hot S13 YC companies that either built their web app in Rails or explicitly deal with Rails (not sure if One Month Rails is built in Rails or not, but it is pretty explicitly pro-Rails). Does Rails prevalence preclude Ruby from being a dying language? Depends on what you mean by dying. The dominance of Rails is probably something of a blessing and a curse for the broader Ruby world. I'm too new to it to have a strong position, but I will say that as a novice developer, I went with Ruby and Rails because there is a fantastic suite of tools for learning from scratch.
I never would have been exposed to Ruby if not for Rails (I'm a novice, self taught developer). While everyone talks about how amazing Scala and Haskell are (of which I have no doubt), I learned Ruby because Rails allowed me to build little projects (usually web apps) very easily. Now I have branched out into a bit of node.JS, some Python, and some Clojure (I like the idea of learning a Lisp), but Rails was a friendly entry point.
Well there's a broad range of applications that simply can't be built with Rails. And that's shame. It's a corollary to the other commenter saying that Rails no longer fits the new web programming paradigms.