We get different studies about how Generation X, Millenials and Generation Z consume sports. But the general rule seems to be: the younger, the smaller the attention spans, the less trust in governing bodies, the less live consumption on TV (legal and illegal streaming), the more social media and highlights consumption.
McKinsey says that GenerationX and Millenials are very similar in their sports attitudes and even in media behaviour, although they also diagnose a) significantly more streaming than linear TV on the Millenial side and b) significantly more social media activity around sports for Millenials.
At the same time, PWC sees total disruption imminent because of younger generations and tech development in their 2017 Sports Survey
Full PDF: http://www.pwc.ch/en/publications/2017/pwc-sports-survey-2017.pdf
German article: https://www.sponsors.de/pwc-studie-junge-zielgruppe-bedroht-sportbranche
With regards to business, besides the "media packaging" that needs to be done to attract younger fans, two are also worth mentioning:
65% of 18-34yo stream Premier League matches illegally at least once a month (see link below). Even McKinsey points out that "converting the pirates" is one major activity to focus on.
And trust in governing bodies is decreasing (PWC study) heavily and should be of major concern (for both the governing bodies maybe intending to stream / sell matches themselves one day, but also for media acquiring rights).
Edit: One more research from Deloitte, Full PDF - https://www2.deloitte.com/content/dam/Deloitte/us/Documents/consumer-business/us-cb-deloittes_sports_industry_starting_lineup_2017_final.pdf