No, loosing a HYD SYS on an a340 would, ad definitionam, of course not be an ETOPS problems. ETOPS refers to TWINS, hence the meaning of ETOPS!
I still wouldn't take an A340 running on 2 HYD SYS only across the Atlantic or any other remote part of the world. Why do you think they give it 3?
And 767jock:
"is it wise to leave an hydraulic system leaking everywhere inside for 7/8 hours ? "
Do your homework please. If pressure cannot be restored, the QRH directs that all the associated system pumps are selected off.
Well, before you tell others to do their homework - how about a deep long meditation on HYD SYS functions - is there not a reservoir pressurized to even out the bumps? Wouldn't it be pushing the soup out, and wouldn't it be flowing out after time anyways? And why do we switch off the pumps? To keep the fluid in the lines? No, sir, you switch 'em off to keep them from running dry and getting ruined...