1) Rails (I don't know Django) will continue to be the quickest way to have a quick full-stack demo/MVP. It is opinionated, and has tools like railsapps that let you customize it. So you can have a solution that includes bootstrap, authentication, stripe-payments, etc., almost completely out of the box.
2) Rails will continue to be plagued with the problems (security, slow dynamic language) etc. but it will always have workarounds like jruby, celluloid, rails-api, in-memory-models (I wish this was more common). The community is vibrant enough to keep plugging along and fixing the gaps.
3) I don't think it's a coincidence that the two most influential frameworks (Rails and Sinatra) were written in Ruby.
4) Eventually people's MVP will move to something like Scala, following the example of Twitter and LinkedIn. Static languages that encourage functional behavior improve speed and safety.
5) Play is interesting. I am checking it out now, and seeing how I can move a rails app to it.
6) Node serves the lowest-common-denominator in my opinion (it caters to non-polyglots). I use it for certain things (a workflow for prototyping phonegap apps, and client-side tooling) but I personally think it is way overhyped. However it definitely has a place, and will continue to have one.
7) If Rails does someday "die" that's okay for dhh's legacy. His framework is spiritually part of whatever comes next and raised the bar as much as Seinfeld did for television.