Exchanges are sidechains.
Very good point.
It also shows if single nodes get too big, they become attractive for hacking. Lightning network should automatically flatten this out a bit.
Funny we did not see wallet to wallet transactions via exchanges yet. Or did I miss sth?
Thanks and right. There is indeed some wallet to wallet instant transactions. For instance, on Coinbase you can send bitcoins to fellow Coinbase members. And using just their Coinbase email address as well. And the transactions are instant because they are done off-chain. Kind of Paypal like. That's another thing Lightning and side chains could potentially do, which is introduce some familiar transaction conveniences that first generation blockchains do not accommodate themselves.