The dating game is radically changing. It's hard to predict what will happen in the future. Right now, there are so many unmarried singles. Right now, there are so many young male virgins. The body counts of women are also sky rocketing, etc.. etc..
I agree, PAST data suggest in general the average young woman is marrying a man a few years older -- that is what the PAST data suggest. However, "past performance does not guarantee future performance". I have noticed a trend of younger women with radically older guys. Remember, it was only a few generations ago that 16 year old's were getting married:
Change happens. If I had to predict, I feel the age gap between men and women dating will widen. In the past, if a young girl wanted to date/marry an older guy, she probably couldn't. Why? Because that older successful guy was already married. People got married in the past quickly and stayed together due to societal pressure (which I think was probably a good thing for the benefit of both the children and the parents).
Right now, a lot of young men cannot compete with older successful guys especially older men who are in shape. In the past, older successful guys would have mistresses or flings because these guys were married; now older men are more likely to be unattached. Also, unlike the past, younger women have more exposure to older men. Either through social media, dating sites, etc. The world is more connected and people accept wider age gaps.
It is predicted that 65% of women over 40 will be single (something like that). Indirectly, that means there's going to be a lot of older guys available. That young babysitter who thought that the dad of the kids she's babysitting was hot, but she couldn't do anything because of the wife. Well, there's a good chance he doesn't have a wife. Or the young lady who has the hots for her older male boss, in the past he was probably married. Not now. There's a higher chance he's single. There's less obstacle for her to try and hook up with him.
Will the majority of relationships have a wide age gap? I don't think so, but I think there will be a lot more than they are now. Perhaps 10x as much. But they wouldn't be the majority. Successful men of any age is rare even though older men are more likely to be successful.
At the end of the day, in general men want fertility, and women want RESOURCES and STABILITY. If we accept this premise, the only conclusion is that we will see more relationship with wider age gaps especially if going forward more relationships become casual. A rich successful older guy can date many young women especially if he doesn't have a wife to worry about or society telling him to settle down. Also, there seems to be a trend for younger women to "wait at the goal line" for the winners; instead of dating and marrying the younger broke guy and then working with him to become successful together..
Remember most guys who are "winners"; it takes time and age to "win". A lot of these winners will be older.
The real looser in this new game will be the older women who did not pair up at all.. They will have no one.
Just my 2 cents.