They could make some pretty big financial savings in this area
Sadly, its not so much "what they need" but more "what they are feel they are entitled to" as part of the 8%/92% split. It will be used as a bargaining chip in negotiations (much the same way the subs at Faslane will be) - we (iScotland) will give you (rUK) what you want (subs remain at Faslane, Typhoons south of the border etc) if you give us what we want (currency union, shipbuilding contracts etc etc).
All of this will, of course, be irrelevant in the event of a NO vote.