Although the business class seats are a previous generation I have found them to comfortable for Friday 3 hour evening hop to Bangkok - the Economy seats were replaced in 2019 and these aircraft of course do not fly long haul routes . Personally I consider the aircraft perfectly fit for purpose however a new aircraft are always preferred but would I fear offer no more room in economy.
Over the past few years there has been some 'noise'. about more than one CX variant of the A350 but nothing concrete has ever emerged.