The whole electric typewriter thing is kind of overblown. As soon as they're going (and they're probably already going in the basement of the War Department), the support devices (vacuum tubes, whatever) will be very large and they'll be limited to very specific research applications. There's going to be a technology divide: the masses will still be using slightly better variants of the machines we use right now while MIT will be using punch cards. Even in the distant future, people will still be doing Mail/word processing on non-electric typewriters because why would you need such a thing in the house? Think about it: there are machines in the world that can freeze water solid, but all I need is an ice box keep my cider cold. Anyway, I think your investments in the Dow Jones Industrial Average are pretty safe for many decades to come.