The Rails ecosystem is definitely battle tested and not going away, but Elixir/Phoenix is kind of a Rubyist's way of not dealing with any of the scalability downfalls of Ruby.
Ruby itself will deal somewhat with its own shortcomings year after year, and performance is supposed to be a big part of 3.0, but it will never be architected for certain usecases.
The Rails ecosystem is definitely battle tested and not going away, but Elixir/Phoenix is kind of a Rubyist's way of not dealing with any of the scalability downfalls of Ruby.
Ruby itself will deal somewhat with its own shortcomings year after year, and performance is supposed to be a big part of 3.0, but it will never be architected for certain usecases.
Kind of an inherent "it depends" kind of answer.
Thank you for your response Ben.