When I think about people I meet from south India who know about Bhangra while my native Punajbi people don't know a scintilla about katha-kali or kuchi-pudi, I cannot but accept the fact
"I believe that the change in dress habits is part of the growing Punjabi-isation of India."
Sanghvi is also right in saying that
"But equally, I am not prepared to say that Punjabi-isation is necessarily a bad thing. But it’s worth thinking about, isn’t it?"
I think 'cultures' evolve rather than dominate one another. Like Punjabi culture is a mess of Mughal, Sikh and Hindu culture constantly invoked by invaders who came to India via Punjab. Yes, it is a mess and there exactly lies the richness of culture. Maybe intrusion of Punjabi culture in others is actually evolution of other cultures and that of itself too.
And by the way, the essential Punajbi culture is not about Indian Punjab but the bigger Punjab region.