The alt coins would be a representation of a stock. If you hold a coin, you really hold a stock.
Let us say Company Taco Stand wants to sell 1000 shares of stock to get funding to open a second taco stand. What they will do is premine 1000 alt coins and then trade them for BTC.
The free market would set the fair value on the stock of that company.
So each asset issued would require its own blockchain? Trade fees won't be enough to bring too many miners in. Someone could easily 51% the alt-chain and invalidate/steal the asset.
Not trying to play devil's advocate, just pointing out a possible problem.
Clearly if we take this path we will need the support of the community to keep that from happening, however we have a couple of other options that might work better.
One option would be to just make a master alt coin and have it trade freely like all other alt coins. However make it so, when ever this gets mined they have to mine the other sub alt coins.
I think some community support is possible, but many people easily control ~25-50 GH, and getting enough miners to kick 25-50 GH (enough to prevent a 51% by the former) towards an asset's chain for no tangible reward seems unlikely, especially when assets start to crop up in large numbers.
The concept of a master alt coin seems much more viable in the sense of less susceptibility, but less viable in the sense that the whole exchange would be reliant upon it. (To say nothing of the technical difficulties.) I just can't see enough trade fees to support ~250 GH of miners, which is IMO around the minimum needed for bare minimum protection from a 51%. Maybe after a long time in operation and a significant expansion in the number of Bitcoins invested, but certainly not at the start.
For example, about 100k BTC have been invested into GLBSE in the last month. (No, this isn't a calculated number, just an estimate, pinpoint precision isn't important here.) If we assume a similar volume, at a trade fee of 0.5% (excessive), that would mean 500 BTC a month, for the whole chain, which would translate to a little under 30 GH/s with equivalent profits to direct Bitcoin mining.
30 GH/s is
extremely 51%-able. (Interestingly, spell-check doesn't consider that incorrect. Google Chrome coder = Satoshi?
)
I don't think people would feel comfortable investing with that level of vulnerability.
Again, I know I sound very negative, don't take it too harshly. I really want this to succeed, and would be glad to do whatever I can to make it possible. It's just important to have these discussions now, rather than after a catastrophe occurs.