Handshakes: my mistake: (n-1)(n)/2
So, 5 people is 10 handshakes.
And 10 people is 9 times 10 divided by two, or 45 handshakes.
As you can see, it goes up fast.
What are the sunk costs?
Do you default to open or closed systems?
What's the sea change that's going to eliminate lock in?
Are you willing to invest in creating a network effect?