I wish something would, but nothing at the moment, is even close to the scale at which rails gets things done. I truly mean it. And something built out of Javascript replacing a Ruby-based full-bleed framework? I think you must be fucking kidding me. What the author describes is a very specific use-case and maybe, just maybe Meteor JS might replace a portion of that use case. In fact, if I were to do something like what the author suggests, I would still choose rails and Knockout JS (or Angular JS if you know it better).
Do you know how long it takes to build a Facebook backend clone in rails? Maybe a day? And the frontend (all the Ajaxy stuff) should probably add a week or two (worse-case scenario). That's just it. That's the power of rails.
If you were to build the backend in Javascript without the power that Rails provides I'm sure you will need more than just a day, let alone a week.
The point is, nothing is close to what rails is right now. I badly wanted something to replace rails for my work, but I haven't found a single solution that fits my needs. I've tried everything - Play, Sails, Revel, Gorilla, etc etc. But nothing there is that can replace rails. And all the frameworks that claim to be more like Rails, they're simply not true. Have you tried using play (Scala) and PostgreSQL together? The experience is nothing like Rails.
I can make a clone of any complex app out there in the web in a matter of minutes/hours. That's the power that rails gives me and no other framework/combination can't.
I understand that Rails is slow. But this is not the right way to critique it - Claiming something is going to replace it when it actually isn't true.
We develop all our v0.1s in Rails in house and port them to Go (only if necessary and if the project owner is particular about it.) and that seems to work well for us.