I think that the links between these languages do make it easy for people from the Netherlands, Germany and Scandinavia to learn English. These countries, to give them credit, have also seen the importance of good language education, in particular English learning, for a long time.

There is also an effect which people from other countries have described which makes it harder for foreigners to learn the local language. If you approach almost anyone in the Netherlands and speak to them in semi-competent Dutch, they will often respond in fluent and nearly accentless English. This includes older people, people with only high-school education, people in official positions. So not only do you not need to learn, you are discouraged from practicing by the local population's competence and hospitality.

It might feel that way if your main experience of Germany is Berlin, but is not a risk for any of the rest of the country, including Munich with its fairly strong English-speaking expat community - Germans speak German to each other, and will politely ask you, the non-German, if it's ok to continue the meeting in German, but expect you to at least attempt to learn it.

I've not spent enough time in the Netherlands to speak to Dutch's future, but a big difference I can see is television and movies, even on streaming services: popular US shows are dubbed into German and it takes a bit of doing to get some of them with the original English soundtracks; Dutch has long been a target for subbing.