Flash loans are not a real world application. They are just another tool needed within the cryptospace itself.

This is the problem currently. There's ten thousand teams building and building, but each one of them is building yet another library or yet another tool. Nobody has any idea how to connect the crypto economy to the real world economy.

The only applications possible are ones that you can do within the cryptospace itself, like lending one crypto against another, or creating some creative gambling game.

Unless somebody can figure out how to bridge the cryptospace to the real world economy, the whole castle of cards will eventually crumble.