Back in 2017, I was in the same situation. I was working as a ROR developer but I was also afraid because at that time most people were saying ROR is dead and it has no future. Now it is 2020, I am still working mainly in ROR, and ROR community keeps growing.
Here is a simple rule if the technology keeps evolving and people are using it regularly then it is not going anywhere. Still, a lot of startups are using ROR and they prefer it over other technologies.
I have also attached the link to the question that I asked almost 5 years ago on quora. Maybe it will be helpful for you.