Under the rules of the current world that we live in, administrating any form of financial business requires approval and requires the so-called institution to register with the respective financial authority of the country it is residing in. In well known cases this can be FSA (UK), SEC (USA) or any equivalent financial authority.
Operating an exchange platform would mean that money has to move through it (third party funds) and stored on a medium of exchange (a bank) which would be operating in a country (thus being regulated by a financial authority).
Therefore I dont see how anyone successfully, long term, and stable (from a regulatory point of view) would be able to operate without downtime.
I don't understand the jump you make to say that a regulated exchange would not be able to operate without downtime.
Personally I think that well regulated institutions will be necessary for the Bitcoin economy to grow to anything substantial as they will bring the levels of trust that the general public require
My bad. I ment to say that it would be impossible to operate an exchange service without downtime, unless that respective exchange service was regulated, thus it would be left to do business as usual. If an exchange service pops up and is not regulated, we can only assume its going to crash. Either technically or regulatory.