that would still only account for a 6x increase in revenue-- not the 10x increase that they need to fulfill their contracts

Assuming you're talking about the $600 billion or so over the next decade, they don't need a 6x increase to cover that, they're already pretty close based on the $65B run rate as of last quarter.

their revenue is super concentrated in just a few customers

20% for the top two customers is not actually that concentrated. If both of them go to zero, at their current growth rate (45% from Q2 to Q3) it would take about 6 weeks to replace that revenue.