don't forget .money, .cash, .bank, .financial, etc, etc... AND .COM, I can see BIG potential.. but again,, we go back to .COM
bitcoinexchange.com and bitcoin.exchange
I like the extension. Bitcoin is a good choice based on BTC sale. I have a few dot exchanges.
backlinks dot exchange
links dot exchange
sharemarket dot exchange
It sure works with BTC, bitcoin, probably ETH too. But it's all matter of market saturation and I'd say there is small chance to sell .exchange with lesser cryptocurrencies like Monero or IOTA. Or longer names like goethereum, cryptocoin etc...