They could use North Korea "attack" to justify more local measures, you know, banning encryption, tighter regulations, more penalties... more or less what has been happening last weeks.
I absolutely believe that attacks are used as conveniences to justify legislative wishlists, but question whether such things are planned in advance like you are suggesting or are opportunistic responses to actual events.
Regarding encryption bans I've mostly seen justification referencing the Charlie Hebdo attacks (which are assuredly not a false flag).
Personally I believe that North Korean sympathizers were behind the SONY attacks given a number of pieces of evidence, but most heavily the #GOP leaks of emails detailing SONY collaboration with the US State Department and RAND Corporation that point toward The Interview being a strategic diplomacy product.
