I think it's easier to unseat Bitcoin than Facebook. With a cyrpto currency, it seems like all you would have to do is make mining more profitable on your currency than on Bitcoins.

exclusivity. it'll be a coin launched only on Harvard at first

Nothing, and it's actually easy to make the argument that that was the intent, in the open source, freedom of choice, no centralization, heck the powers kind of environments Bitcoin became popular through.

There are plenty of coins already that are technically better than Bitcoin. It's just that Bitcoin has the network effect.

So perhaps one day a new coin will overtake Bitcoin, but my guess is that the coin will need a very distinct advanatge to gain traction.

Why would that necessarily be a problem? If it's a form of money, to be exchanged for goods and services, why does the specific currency matter? For most people it could be just like switching from Francs to Euros, say -- a little disruptive in the short term but overall no big deal.

If a competitor is able to fix some of Bitcoin's serious problems, it deserves to win. Though I can understand if you're worried about competitors that lack some of Bitcoin's key properties.

You need to bootstrap the infrastructure by convincing miners to join your cause. A well-heeled entity could just offer fiat money (which miners apparently still like), a less well-heeled entity could somehow differentiate at the mining level, e.g. by designing proof-of-work algorithms that would work on home GPUs or CPUs (and thus be accessible to billions of home PC users) which is what Litecoin and some others attempted to address.

The deflationary aspect of Bitcoin will probably get in the way at some point - hypothetically, if you owned BTC and USD today, why would you ever spend a BTC? Spending even costs you money (in transaction fees), while saving doesn't. It's the system that rewards hoarding.