None of my comments are direct responses to anything that has already been written on this topic. I am simply sharing a perspective that might clarify a couple things.
20th and 21st century calligraphy guilds have never been and currently are not organizations that will give members the education or tools needed to build a serious career in calligraphy/lettering arts. Guilds are clubs to welcome newcomers and provide camaraderie for the intermediate and advanced scribes. Many volunteer hours are required to keep the guilds going. Guilds are not run by professional scribes. Top-notch professionals do not have time to run guilds.
It is not fair to blame the demise of guilds on contemporary trends or the failure to embrace contemporary trends. Some guilds die a natural death because the founders have moved on and the remaining members do not have enough intermediate and advanced scribes to keep things going. Guilds in large urban areas tend to have an easier time maintaining the group because of the larger population, but there are examples of very small guilds in remote areas that have been very successful for many years.
Each guild will decide on their own if they want to be more traditional or branch out into more contemporary trends. Contemporary trends are no threat to the traditional arts. They coexist peacefully. People are free to embrace one or the other - or both. IMHO, fretting about contemporary trends is a complete waste of time. Those who put in the hours to really master the traditional styles are simply people who choose to put in the hours. If you don't have the time, there is no crime in puttering around with the easy stuff. Ballet dancers do not look down their noses at the square dancers or line dancers. If you only have the time and skill to square dance or line dance - that is still better than just sitting on the couch with your beer and Cheetos in front of the TV.
Sites like Behance are filled with calligraphers/lettering artists who are doing just fine without guilds. If you aspire to be a professional and make a decent living, you will find the classes and mentors that will further your career. If you think a guild will give you all the education you need, you are most likely going to be very disappointed when you take a few local classes, build your website, and then wonder where the customers are.
This will sound harsh, but it is true. Artists are a dime a dozen. When I was a young graphic designer, right out of college, my first boss made that comment. I was in shock. I thought I was special. But he was right. By taking an objective look at my work compared to the work of the designers he hired to work on the big budget jobs, I could see that I was a *farm team* artist working on the little jobs for the clients with little budgets. It would have taken a lot of work for me to become a big-league artist.
That's how the world works. No matter how much you love what you do, there are a ton of other people who love the same activity. There will always be a lot of competition in the world of art and design. If you want to be top-dog in your chosen field, you will have to work very hard. Your local guild will not be your stepping stone to a successful career. The majority of people in guilds are hobbyists. Personally, I love the hobbyists and I am happy that the guild system is chugging along. Guilds offer so much to their communities - but they are not organizations created for professional scribes or to help those people who aspire to be professionals. The rigorous training required to be a professional would not be very welcoming to most of the beginners or those who simply want a club to support their hobby
Hopefully these comments do not ruffle any feathers. I've been observing these topics for 25+ years. Anything relating to art tends to generate strong opinions - but there is a lot of common ground if people want to look for it.