Many big-blockers are using the phrase "vaporware"; if I've understood it right we do have "proof-of-concept", but it's a long, long way until we can get "lightning support" into the more popular wallets.

Vaporware means something that doesn't really exist. And we already have real lightning transactions on litecoin blockchain, not to mention numerous testnets. I do agree that critical mass is important in order for lightning to truly shine. I think as soon as major wallets update their software we'll see adoption skyrocket.

(Lack of) network effect - I believe that in one year time it will still be more probable that two arbitrary parties can transact through some alt-coin than through lightning.

I understand your skepticism, but I think in one year we'll see two large ecosystems emerge: the bitcoin ecosystem, with numerous bitcoin forks (like litecoin) entangled with the original chain via lightning networks, and the ethereum token ecosystem. Ethereum will most likely be more popular in the western world, while bitcoin's ecosystem will have a stronger support in the asian world.

The lightning network do need some on-chain capacity - moving bitcoins into the lightning network takes two on-chain transactions if I've understood it correctly, and if one is not able to close the lightning channel the funds aren't secure. With bitcoin fees just growing and growing, this may be a major problem.

It does take two transactions to set up and teardown a payment channel. However, payment channels themselves have expiration dates, and once the channel times out your funds will be released to you. While a payment channel is active your funds are secure, but you cannot spend the amount you've staked to open the payment channel until you close it.

One has to move funds into the lightning network to be able to use it there, and out of the lightning network to be able to use it as bitcoins (if I've understood it right). With this constraint, the Lightning Network is not much different from being an alt-coin - one can move "bitcoins" around using i.e. ripple, bitshares, ethereum and probably lots of other altcoins.

It's kind of like an ultrafast altcoin, except without its own token. The benefit of a lightning network is that you don't need to use exchanges in order to achieve these fast transfer speeds, and you don't need to pay fees on the altcoin blockchain. Moving funds in and out of lightning network will be a simple, streamlined process from a user's point of view. Take a look at "zap wallet" prototype that litecoin's community is building.

Centralization risk; the easiest way to get connected to the lightning network in any meaningful way will probably be to connect to the largest hub available. Hence we'll end up with one (or in best case a handful) of hubs routing almost all of the traffic.

That is true, and this is why lightning network is not an altcoin killer. For some transactions it makes more sense to do them slowly, but anonymously, i.e. using Monero. For other transactions, like buying a cup of coffee, you'd probably use the cheapest and most convenient option. Different scenarios call for different solutions.

At the end of the day both you and I are simply speculating at this point, only time will tell how this all turns out. And that's the most beautiful and exciting aspect of modern cryptoeconomics.