It literally says this in the website your linked

> Current actual throughput is significantly lower, estimated at around 300 TPS, because the network is still growing. However, Lightning's architecture scales horizontally: as more nodes and channels are added, capacity increases without any protocol changes. The network's total value locked has grown past $500 million, with over 15,000 active nodes and 50,000+ payment channels.

The layer 2 has been predicted by one of the first adopter in 2010 so it was always the plan

https://bitcointalk.org/index.php?topic=2500.msg34211#msg342... It can scale without any changes and if there is demand it will surpass Visa and MC