Don't for get that SQ bumped up frequency this winter back to daily and QR were meant be increasing capacity to A330-300s.
Most of the airlines will want to see these kind of occupancy rates maintained for a reasonable (12 months minimum) length of time prior to them boosting capacity or frequency. Besides, we know both SQ and EK are suffering from a lack of equipment...this could be a good thing, as the extra 3 flights SQ are looking at become more likely as and when loads stabilise around the 90% to 95% mark; EK would probably be in 2 minds - a 3rd service means an A330 which could otherwise be used for a new route or an A380 onto EK17: the effects of either would result in around an extra 450 seats each day to be filled!
QR and EY would probably want to bed in their services further - what they plan is open to conjecture. Being fanciful, if QR are interested in EDI at 4 weekly operating 2 morning and 2 evening services, perhaps it might not be out of the realms of possibilty that they may be looking at other services to boost frequency.
CO and DL are probably going to be restricted in upgrading aircraft whilst they are after potentially more lucrative services that require the range or configuration of larger widebodied aircraft.