BPMN has played and plays very positive role in popularization of BPM in general and its wider adoption. As any practical and democratic movement, often far from academia, BPMN is used by many companies to solve their practical BPM problems. This natural usage alone should result in a gradual evolution of BPMN where it will eventually fill its perfect niche of relevant use cases and applications.
BPMN relevance is evidenced with its wide acceptance through all major BPM vendors and impressive capabilities of model interchange by all these vendors (over 20 vendors at the moment).
BPM is a rapidly growing field of notations and standards. BPMN is a notable member in this family, not more, nor less.