New Leaders? China, India, Philippines.

Why?

They have growing middle income aka 'middle class' consumers.

People coming into money. Companies will adapt to provide that group.

Old? USA, UK.

Even Mexico City is a cooler city right now.

Youtube is probably the most popular website online. And most viewers are not from the USA, they are from India and Philippines. Sheer population numbers. 1.3 B in India and 300 M in USA. Do the math.