It's become fashionable to hate on rails, and honestly I understand the motivation--it isn't cool and cutting edge anymore. It's slow. It doesn't do concurrency well. Ruby is nice for what it is, but it lacks the power and stability of functional languages, and lacks the performance of go or javascript on v8.

But rails is just doing what it's always done: trying to optimize developer productivity for front end web dev and routine web tasks. In this it's far ahead of the pack, and for many businesses, both small and large, this is exactly the right thing to optimize. Say what you want about github, but they push a lot of features and push them fast.

Rails is not for crafting algorithms, but when you need to crank out 6 new pages with various complex crud views and forms by Friday, and by the way can it be exportable to cvs and oh can you also do paypal and oauth integration and user avatars with thumbnails, and keep it all reasonably readable and organized... the sad fact is that for all of rails' heft and lack of cs cred, trying the above with any other framework after you know rails will drive you insane, because despite how great the language is or how many connections your server can handle, you are again and again spending days on things that take an hour in rails.

Ultimately, I don't think the way forward from rails is to search for a partial reimplementation of rails in some other language. Rails is the best we've got for rapid front end and shallow back end work. So use it for what it does well. For what it doesn't do well, use something else. Personally, I think it's silly to have an ORM written in ruby. ActiveRecord is for the most part a lovely api, but its guts should be a separate service written in go or something. Building a complex recommendation engine or game AI? Write clojure or haskell services. But when the data comes back and you need to dice it up and lay it out as html, with a hundred little ohs and ifs and buts, it's not a fun time without rails.