The Dutch were ridiculously bad at imposing their language on other countries. Little trace of it remains in Indonesia, or New York. Aruba, Curaçao and Sint Maarten have never taken to it. South Africa is kind of the exception except even then Afrikaans has played second fiddle to English for 150 years, and they have sought to differentiate their language from Dutch in more recent times.
Portugal has been better at that game when you consider its size.
It already is, mate. There are people who move to countries such as the Netherlands, Iceland and Sweden and insist on using English all the time. I've even heard of Dutch using English with each other. There are people who've attempted this in Spain, but it's harder there since there are so many Spanish speakers.
Every language has strengths and weaknesses. Perfect is the enemy of good. If your definition of 'good' is 'relatively easy and technically international', Esperanto is very suitable. (Not to mention way better than the status quo, in any case.)
If we follow your line Dutch will go the same way as Welsh or Basque.