I agree with everything else others have said. People are marrying later, having children later, and often couples have not children or people never marry but stay together. This means that parents will be older as their children grow up, or children will grow up in households where their parents are living together but not legally married. I also think that homosexuality is becoming more and more mainstream and accepted, so there will be more families with children.
I disagree with access teacher to some extent. I believe that we already live in a society where the idea of family is not "family" but actually family. Our culture has grown and changed as has the definition of family. The word no longer has the traditional meaning of earlier decades. I think there will become an increasing number of this new type of family. In addition, I think many households will become "family" as two households combine for no other reason than expediency.
If current trends continue, we will see an increase in the number of "families" that do not fit the current definition of "families." We are seeing in society today a massive increase in single parent families, or reconstituted families (where two single parent families come together) or families where the parents are same sex. It is likely that as society progresses, we will see the definition of the word "family" continue to change.
Statistics are showing that compared to the last 50 years, there has been a decline in marriage across all socio-economic statuses; however, the decline has been greater among lower income groups.
Single-parenting is not taboo like it used to be, and many women are putting their careers at a higher priority and choosing to have children later in life. There is also a need for 2 income families, rather than just the father working outside the home. This may be a reason as to why many couples are opting to have fewer children.
The divorce rate is dismal and step families are also very common. I think these trends will continue in the years to come as society's views, way of life, and standards change tremendously. The economy also puts a lot of strain on families. It's hard to predict what the economy will be like in 50 years, but I think finances, jobs, housing etc all have a major effect on family structure.
I personally believe that in the next 50 years, the gay marriage "issue" will no longer be an issue. The fight for equal insurance, inheritance, etc. rights has been long in coming, but has made enormous gains in just the last couple years. Consider that much of the voting population in 50 years isn't even alive yet. Add to this the thought that if the trend in the media to make it a normal part of family life in prime time television continues, the idea will lose most of its "shock and appall" value.
50 years may not bring an end to the struggle between those who are for and against it, however, I do believe more states will legalize it. In the same way that our conservative society has slowly become desensitized to violence and sexuality in the media and in video games, I predict this issue to eventually become more and more accepted.
I think that with the state of the economy we will see smaller families also. I think the days of the large family are numbered, unless the economy improves. It is currently a struggle for the middle class couple to support a family of three or more children.
We can make a few predictions, rudimentary in nature, based on some current trends. The divorce rate peaked in the early 1990s, and has been slowly declining ever since then. What's more, the average age at which Americans now get married is 26. This makes, in my opinion, the institution more stable and successful, so I expect we will see, barring some catastrophic economic or political collapse, less divorce in 50 years than now. That being said, it's really anyone's guess.
This is, of course, very hard to predict, given that no one 50 years ago would likely have been able to predict the state of the family in the US today. However, based on current trends, the family 50 years from now will be a different thing for the "haves" and the "have nots." The "haves" will have relatively strong and stable families while the "have nots" will suffer from more divorce, more births outside of marriage and other such ills.
A study that I read recently shows that people with more education (those with at least a bachelor's degree) are much more likely to be happy in their marriages and to have stable marriages than those with lower levels of education. This report can be found in the virginia.edu link below. If this trend continues, the less-educated of America will have less stable family lives, which will hurt their children and give them less of a chance to succeed.
Based on current trends, there will be two American families in 50 years -- a stable one that is seen among well-off people and an unstable one that is seen among (and hurts) the working class.