Duo bands are a trend. I'd like to think that royal blood's chart success will shed light on other rock bands in the music scenes. But rock music in the mainstream is not always a good thing. I can't imagine some pretty boy townies throwing on some band t-shirts and start listening to rock bands. People don't want to be called out as hipsters, but looking back at other music scenes in the mainstream/pop culture, mass idiots following trends usually end up in the bastardisation of something unique.