If it's not your private key, it's not your money. So yes, if the exchange doesn't come back up you can pretty much write it off.
[0] about $20 when I put it in IIRC.
No, it's not what OP says... He's saying security and convenience are mutually exclusive in BTC. I'm saying that is not the case... You can use an exchange and transfer or use a hardware wallet with built in exchange capabilities. Making it seem like there is some inherent issue with the design/architecture that makes this impossible is extremely misleading.