Bottom line, I have learned in the last 3 years living here, is you need to speak the language, how well depends on you and what your living / working environment is. Granted, it's not easy for some people to learn languages, like me, same is it's not easy for some people to learn how a car works. Think about it this way, how would you feel if foreigners came to your country and insisted you speak their language. The Dutch is atrocious that I am of the moment speaking, and I can't yet write it to save my life, but I have learned to laugh at it, and the people I speak to appreciate the effort and then we laugh together and maybe become friends, and maybe get drunk together and generally have a nice time, and only if they offer to speak English, will I hesitantly accept the offer, but will switch back and forth, and so the ice is broken. I was at first very shy and embarrassed about making mistakes, so I kept quiet, but then I threw caution to the wind and just let it out, and so your confidence grows, and each time you see the same people you get comments about how your Dutch has improved, and so your confidence grows even more, and the more you are able to embrace the new culture you have chosen to live in.
Now even though some dialects are impossible even for native Dutch speakers to understand, all you have to say is 'wablieft?' and 8 out of 10 times they will repeat what they said in plain Dutch. Recommended movie: 'Rundskop', if you want to hear St-Truidens dialect, I had to read the Dutch subtitles, good Belgian movie. Wouldn't the world be boring if we all spoke the same language? I find Belgium fascinating, the more I learn about it. I would strongly encourage all newcomers to do whatever you can to integrate, you will be surprised. Here in Limburg I went to 'Inburgering' for free as well as free Dutch lessons up to level 2.3
The Belgians are a lot more welcoming of foreigners than you think, and I am saying that based on my own personal experience. Many years ago I met a Belgian girl in South Africa, my country of origin, and got married there, then after some time decided to come here. Of all the countries I have ever considered living in, Belgium was not one of them, however, I'm pretty sure deciding to live here is one of the best decisions I have ever made.....amazing beer, blazingly fast internet, huge public libraries that cost just 5/year, great food, lots of jobs, at least ones that more than cover our frugal standard of living, etc. (I have a 7 year old 'hand me down' cell phone that still makes phone calls, what more do you need?)
Having put myself in a Flemish Belgians shoes, so to speak, it has helped me understand things from their point of view.
"Spreek Nederlands!"