Was listening to theycallmedan the other day, and he was mentioning lightning and shared his thoughts about it. His thoughts are something to take into consideration, that eventually Lightning as a layer2 may end up being a less, but still centralized payment gateway.

Yeah, I listened to that too. He isn't very precise with the critique though. Centralization of what? Lightning is a completely open and permissionless, like bitcoin. Unlike with traditional banking system, you need no license from the government for sending, receiving or routing payments (on the protocol level). Only capital and know-how.

If his critique is about centralization of liquidity, well that simply isn't a problem, because having lots of liquidity gives no power over the protocol. And if an entity with lots of liquidity tries to abuse their position by putting a premium on fees, well, more routers/payment processors will pop up with lower fees and capture that value. Permissionless protocol allows for maximum competition which means you actually have to compete with your service to have a good business.

If liquidity centralizes on lightning, that just means that that entity is very good at managing that liquidity and provides it where it's needed. I struggle to find the problem with this.

One of the biggest signs of that, to me, is that we're still calculating BTC and other cryptocurrencies back to FIAT.

That's simply because BTC is still tiny in marketcap. Once BTC starts to hold a bigger share of individual wealth there's more will to use it for payments. That's when people will start to calibrate measuring value in satoshis. It just takes time.