I may be wrong, but then if the gate was shuts down, or the ultimate trsuted person in the chain or possibly anyone in the chain that I needed to ge to the gateway I am stuffed.....all over
Note that the example didn't contain a gateway. In a sense a gateway is just a user that is trusted by many people, which results in short paths between many individuals. The more gateways, the more robust the system. But even if there aren't any gateways, you can still ripple from person to person. You are only exposed to credit risk caused by the people you've directly granted trust. If someone on the chain defaults, then the payment should still reach you, though the person after the person that defaulted would probably revoke his trust, so that the same thing couldn't happen again.
it seems there would be a point where it would be more profitable for a gateway to shutdown, having lots o btc then trade, so there would be an (increasing?) economic insentive at some point to not not be a trusted gateway....and run away with my BTC. I realise I have he same risk with say gox or btce holding my BTC, but in Ripple is it the case I can have any number of small enties any of which would say, I out thanks for your BTC...!
Yes, trust means trust. If you don't trust a person not to do this, don't grant them trust or you may be the victim of something like TradeFortress's little stunt. And don't just trust a gateway either: they're likely to be less reliable at keeping your money than banks, which aren't terribly reliable to begin with nowadays.