The last smart President
Almost everyone born in the U.S. after 1970 in any socioeconomic class for which becoming President is feasible has grown up using the Web. Almost anyone intelligent and interesting born in the U.S. after 1970 has grown up writing content for the web. Most of which is still out there.
I used to sometimes hesitate before posting something that could be traced back to me, and think, "Having a permanent record of this opinion on the web will make me unelectable for anything." By now there are hundreds of my opinions archived all around the world that each individually make me unelectable for any U.S. public office. Such as the fact that I'm a brony. While the U.S. electorate was ready for a black or female President, bronies are still beyond the pale.
We've already seen that, to be approved by the Senate as a Supreme Court justice today, it is helpful to never have rendered opinions on important subjects, and to have as small a paper trail as possible. This is more difficult for justices, as they have to make judgements and write things down.
In 2020, if the typical presidential candidate is 60 years old, they will have been born in 1960. That's just about the latest an intelligent person could have been born in the U.S. and not grow up leaving hundreds of public posts and comments that can be taken out of context (or in context) to disqualify them from public office.