Linguistically it's hard to see in a sense -- a lot of continental West Germanic areas have dialects distinct enough to be practical languages in their own right. Switzerland's Alemannic is famously distinct from standard German and OTL Germany does have Low German/Low Saxon in its own borders as a definite distinct language. Having Dutch/Low Franconian is just something else added to the mix.
Even a more blatantly German-based Dutch language/Germanized Netherlands might still allow for its independence -- it was a rich trading and industrial area on its own, not to mention faced religious divisions in the past like Germany did (witness Catholic Flanders and the southern Netherlands to this day, and OTL this part of the reason Bismarck was leery of including Austria into united Germany), although admittedly it was still mostly protestant. Anyway, a Netherlands seen as one of the Germanies wouldn't change much, I don't think. The biggest deal would be if Germany got them in unification (but they might not, they didn't get Switzerland or Austria in) and I think if history ran its course per OTL that Germany would still be defeated in the world wars. I can even see the Netherlands split off Germany yet again following the ATL WWII. (Again, it happened with Austria.)
Obviously butterflies can do anything, of course, but given Germany's motivations OTL I don't think it will change much of anything.
Too many butterflies to be realistic, but lets say the Dutch view themselves as Germans ,and therefore are in the CP. All this is stronger if formally a part of Germany.
1) Germany does not need to find a "Place in the Sun". All it has to do is encourage immigration to the Dutch Colonies. Likely no Morocco crisis. There are a few million German immigrants in the DEI by 1910. Even after there is decolonization, there could still be a German speaking country in what is now Indonesia.
2) The four big powers in the far east are America, UK, Germany, Britain. If Britain is allied to Japan as in OTL, the USA being pro CP is likely. Likewise, if Britain and USA team up, then German-Japan Alliance. In the latter case, we have three big alliance blocks. Anglo-USA, Entente, CP.
3) All the Belgium is neutral stuff is different. Belgium is now critical nation Germany plans to get around British Blockade. France is more likely to violate Belgium than Germany. Also, if German Navy is stationed in Netherlands, is Belgium Neutrality still vital to UK?
4) France's national pride was hurt by A-L. If German split Belgium along language lines and Germany gives up a token amount of A-L that speaks french, there is a face saving solution to the problems where both sides can say they won. I can even see Operation Sealion, by the French and German Navy. I can also see a possibility of when the three emperors league breaking up, France joining the CP. France give some/all in A-L, parts of Italy. A-H is conceded the entire Balkens and Venice, German gets some/all of Belgium. All cemented by a major war.
Even if we get to WW1, and the new Dutch/German federation does invade Belgium, the war looks different. It is about 3 extra corp likely active and maybe 2 full armies once mobilized. The German invasion of France goes much, much better.
I believe the Netherlands speaking German and viewing themselves as Germanic massively changes world history. It is not as a profound change as the USA speaking/viewing themselves German or Brazil speaking/themselves German, but it is huge.