A very optimistic exchange rate could be estimated by assuming parity between the "market capitalization" of BTC and XRP. If 21 million BTC have a market cap of $600 million as at present, then 100 billion XRP might have a similar market cap. This would value each XRP at $0.006.
This has probably been answered many times over, but doesn't this make the developers (or whoever has the power to issue XRP)
incredibly rich and powerful?
With ONLY 20% of all Ripples in existence!??
Let me get a calculator...
yes
20E9 * 0.006 = 120 million $
also: coinbase (?) is holding the other 80%. They are giving out chunks of 50,000 to anyone that wants some. Let's say 10,000 people are getting 50,000 each. Thats 500 million. That's still only 0.5% of all ripples, so coinbase is still holding 79.5% after the giveaway.
If ripples are indeed going to be valued at $0.006 that's quite a wealth-grab: 120 million $ for the devs, 477 million $ for coinbase.
I doubt they will be value $0.006, though. The 50,000 giveaway would be $600 for each person.
EDIT: such value would require ripple to be at least as successful as bitcoin. Comparison: taken satoshi has 1 million BTC (5% of all coins), he's now "got" 1E6 = 28 million $.