I don't really care about altcoins (I do hold litecoin private keys). I'm a K.I.S.S. kind of guy. I think it's better to focus on doing one thing really well before trying to add all kinds of fancy bells and whistles. I think a decentralized ledgers best use case is primarily as money.
You see, that's the problem with innovators and mover/shakers, they don't know when to stop innovating and just be mechanics. Coders are mostly innovators. They can't be satisfied with just maintaining/perfecting someone else's design.
Bitcoins best use is simply being money that you can effectively shove in the receiver of a phone and have it spit out 10,000 miles away instantly. That's something that you just can't do with any other kind of money. Bitcoin does that well. The problem is that's not good enough for coders/innovators. They are hell bent on making Bitcoin replace pocket change, stocks, bonds, credit cards, debit cards and those little handi wipes that keep your butt good and clean. Businesses are taking over Bitcoin. They will temper innovation and make Bitcoin work perfectly for what it is first and foremost. Except that kook Patrick Byrne, he seems to be looking for handi wipes.