As for bitcoins valuation, the sky is the limit. 1000+ is possible if it gets adopted worldwide and is used to buy and sell.
why set the bar so low? I heard people on here talking in the neighborhood of $100000 a coin.
The latter is possible but I tentatively predict mBTC-$ parity (or 1000 USD/BTC) within 18 months of now. (Which may or may not be a bubble.) $100/mBTC ($100k USD/BTC) will almost certainly have to wait longer.
15 million BTC x 100000 USD = 1,5 trillion USD. Realistic if bitcoin really gets going, but that's gonna take some time. Gold markets including paper "gold" are roughly 7 trillion USD I think.