The first thing that has to be determined is "who is actually PAYING MONEY" for new pinball machines?
When you determine that then you can easily see why there are virtually zero 'new' artists used for pinball licences.
As far as I can see 20 somethings are NOT the ones buying pinball machines - they spend their money on other pursuits.
So the answer to the OPs question: "When will music licenses catch up with modern times?" - probably never!