With apologies to Samuel L Jackson's character in 1993's Jurassic Park, be prepared to hold on as the WannaCry/Wanna Crypt ransomware scourge is likely just the first in a series of things to come.
The main reasons are that there is more money to be made, and there are still exploits and tools waiting in the wings from the recent NSA "dump". So we can logically expect a continuation of this sort of thing, making a lot of IT department's lives miserable in the coming months.
eWeek“The ransomware payload wasn’t all that novel,” said Jack Danahy, CTO of Barkly Protects, a company that provides enterprise anti-malware defenses. “What they did used a new technique to spread itself using an exploit called Eternal Blue which was revealed by ShadowBrokers.”