You have seen the future, and it is Now
This is going to spread, folks. The Norks have shown the way. Can't keep your country afloat on taxes and commerce? Simply steal the cash from another country! Very soon, another cash-strapped country will start doing this, maybe Burma or Venezuela... someone always follows. One or two more, then everyone piles in. Eventually, affluent countries will find reasons to do it as well, possibly to "recover stolen funds".
It's the old story since humans first threw rocks at each other. Make it difficult enough for your enemy to attack you and they will find a new way to do it. Land wars are expensive and messy. Electronic wars destroy nothing compared to bombing, kill nobody, cost less than one fighter plane's load of missiles and can be totally deniable. It's too good to pass up for long.
World War III will be financial, so to speak. Given the lack of physical borders with armies fighting for land, there will be little reason to form strong alliances. The ones that form will be transient and rather limited. I could be wrong, but I expect a free for all of state-sponsored finance hacking within a decade or so.
Free opinions, worth every cent!