Whilst it is a sad day for the RAF, in the RN FAA it will be business as almost usual. SAR is an inherent part of FAA RW operations and all crews are trained in it. The alert RN SAR at CU and PW will go but you can bet that it won't be too long before a Merlin is airborne on a rescue at CU.
Re Plane Guard - that went out with the old ARK, none of the CVS Harrier carriers ran a plane guard system, although they probably had a duty SAR cab - as does every Frigate and Destroyer with its Lynx or Merlin.
One interesting note is that almost no civilian SAR units have ever won awards for daring rescues (ie Maisie Lewis award, GAPAN awards etc) it has always been the military who seem to have gone out in the most diabolical of conditions.