Complex sentence: Despite this, the theatrical community has faced a decline in recent years following the demolition of Her Majesty's and the Regent Theatres in the 1970s-80s because of the demand for more venues and appropriate stages for productions.
Split into simpler sentences: Despite this, the theatrical community has faced a decline in recent years following the demolition of Her Majesty's and the Regent Theatres in the 1970s-80s. Resulting in the demand for more venues and appropriate stages for productions.