If the OP is referring to SQ's new "Executive Economy" class, it's not a new thing across the fleet. It's the equivalent of other airlines' premium economy products (BA, BR and VS spring to mind) and as I understand it is currently destined only for the A340-500s which are going to operate 18-19 hour long sectors.

If it's a raging success, then I suspect we may see it pushed out across the fleet but only as limited availability additional cost option to normal economy, which is almost certain to remain.