Private Key Bruteforce computational requirements

So as many people may or may not be aware. You can get the indexed values of ALL possible private keys within the key space. Of course building such a database would be computationally impossible, so what you can do is what many do, compute the addresses for a specific page. privatekeys.pw does exactly this. They also have some tools to let you scan for keys containing any amount of bitcoin.

Theoretically the more CPU power you have the more keys per second you can go through. Typically with 4 threads I get about 80,000 keys/sec. Given the impossibly large size of the keyspace that likely finds me nothing after maybe 50 years of searching, However, if I were to scan 1,000,000,000 (1 billion) keys per second, what is the likelihood I find a private key containing some amount of BTC after a month or two?