Opting out of meat entirely does nothing to change the industry, because most people will always eat some meat if they can afford it.
I think opting out does a few things. It puts pressure on restaurants to offer alternatives to meat, so we're not all forced to eat it because it's the only healthy option. It pushes our culture to give people a choice. Honestly, all I really want as a vegan is for people to have a good choice every day, at each meal, about how much/what kind of animal products they consume. Right now in most places there just aren't choices, because 99% of people have a "well, I'll just keep eating what I always have" mentality.
Also, opting out of meat does get me into conversations regularly about the meat industry. The fact that I only eat very specific kinds of meat in specific occasions opens up conversations with other people about when and why they eat meat. I don't care if people eat meat on purpose, for their own reasons, but I do care that they wolf down pounds of it every day for no particular reason because it's what's put in front of us. My opting out creates a context for other people to consider opting out.
And given that's my motivation, I'm pretty careful about how I engage people. I don't shame people, I don't push them. I honestly don't give a shit what they decide. I just like having the options all out there.
Note: I consider myself vegan. I eat meat and dairy sometimes. I eat vegetables, and vegetables are grown with animal products. Meat and dairy are not the basis of my diet. I eat a plant-based diet, so I consider myself vegan. You can call this "reform vegan" to the "orthodox" if you like. But anyone who's really looked at the realities of the situation (including the OP) comes to understand that there is no such thing as 100% vegan, and that what matters most is the health of the whole ecology.