I'd like to add two small things:

• Lightning is having more than 300 Bitcoins in it's channels, so just to give an imagination, what can happen in volume and size off-chain.
• And then there is already the first sidechain ("Liquid"), another on/off chain layer (requires a in and out transaction on the blockchain), which allows for additional transactions outside of the bitcoin main blockchain.

So scaling bitcoin isn't a point of discussion anymore (only for those people, who want to make sure, that the coffee they paid for a dollar is forever visible in a blockchain - for tose people it is better to use bitcoin unlimited, abc or cash chains).