In cancelling South Stream in exchange for a deal with Turkey, Russia is attempting to maintain the economic benefits of a share of the European gas market whilst steering clear of the sticky political issues that accompany it.
The end of ambiguity about Pyongyang's nuclear capacity raises fundamental questions affecting China, the United States, and the future of international non-proliferation strategy. Indirectly, these consequences could actually work to the advantage of the West in its attempts to prevent Iran 'going nuclear'.
The UN Security Council is certain to impose sanctions on North Korea. But, since these are likely to involve – at least initially – just cutting off trade and diplomatic contacts, no significant impact is expected.