Research outside academia without Ph.D
I do not think that you'd be limited in publishing your research results or finding collaborations if you do not have a PhD. You pretty much need a PhD for the academic career path, basically if you want to become a professor some day.
The major issue is if you are able to support yourself doing what you do. And if you can allow yourself to do research, and to do the research you want to do, while working in the industry.
To give an example, Peter Montgomery published his multiplication long before he obtained his PhD, while he was working in the industry, as far as I understand his circumstances.