No one knows how the LN graph will look like until it's widely used. Most people will use LN for micro-payments, this means that people with low amount of BTC will still get used, so you won't need to open a channel with a big hub for you to pay your $3 coffee, because most people will have an open channel with an amount greater than $3.

Even in the worst case scenario where we have centralized hubs, it's a different centralization compared to say Ripple, where for example they can blacklist you and you can't send any XRP in the whole Ripple network, so you effectively have lost your XRP. In the case of a centralized LN network, you can just open a channel with a person that is already connected to a big hub and send all your transactions through that person if the hub refuses to accept your payment, and for small payment, I guess you won't even need a hub, just route your transaction through normal users.

centralization and decentralization can't be measured in absolute terms, all that a centralized network of hubs can do is refuse to route your payment, whereas in other centralized networks like Ripple or Paypal, they can actually freeze your funds.

Even if we have big hubs that most people use, can you really call it a centralized network when you still have the option to choose a route that doesn't involve these big hubs?