Regardless of what shiny new language and framework developers want to use today, Rails apps aren’t going to be migrated to [insert new fad framework here] overnight. Rails has proven it can do all of the things above, just like ASP.NET did. These battle tested frameworks aren’t going anywhere and have nothing to worry about.
Rails has a fantastic user guide too, with a load of Rubygems backing it’s every corner. It has no worries about competition 💪