I get slightly different numbers.
24*365*3600*7*150*1,000,000*((1,000,000,000)^4)=
3.311 * 10^52,
whereas 2^160 = 1.46 * 10^48.
so instead of it taking 150 billion years, it would take more like 150 million years. but who's counting?

I took a second look and the math was pretty FUBAR the first time. Thanks. I limited them to only generating one new addresses a second to keep everything else working right.