The Lightning Network ecosystem is expanding to include all kinds of nifty websites and apps.
Most of these apps are on central servers. They use LN for its payments ability, not to make a distributed application.
Decentralized apps on a blockchain cannot scale to millions of users. Blockchains that claim to support millions of users on the base layer are not really that decentralized. Imagine if Twitter could only have a few hundred thousand users before it became really expensive to send a tweet.
An app like that will never succeed in replacing the status quo. However, it might get big enough to make a few people really rich before totally collapsing.
An app doesn’t need to be 100% distributed to be decentralized. It just has to be NOT centralized. You don’t need a blockchain for this.
Email is not centralized. You can sign up with hundreds of mail providers or even host your own mail server.
Alternatives to traditionally centralized internet services include hosted federations like Mastodon, Funkwhale, and Matrix Chat. They work like email, but instead of sending text and attachments into people’s inboxes, you can make posts on a timeline, stream someone’s music library or post messages in a chat room.
There are hundreds of servers acting as gateways to the fediverse and you’re free to choose any of them or host your own.
And none of it uses a blockchain.
I see a decentralized future where federated apps run on payment servers operated by individuals and corporations all over the world.