its a phase the uk market always goes through
It's like when i was growing up it was all about Brit Pop dominating the charts, in my teens it was the indie wave, its just a cycle unfortunately..
With America, Hip Hop has been growing for decades, their influence has alot to do with the success of uk urban music in mainstream imo.
This could be positive because the Grime/Urban scene are starting to build their own mainstream identity that could possibly emulate a fraction of the influence Hip Hop has had in America.