Something tells me that urdu would have been slowly and surely eradicated in that scenario, like it is in India. Hindi has been shaped into a slang or 'tapori' language, while Urdu in Pakistan still retains its shaistagi. I have many Indian Muslim friends and their 'version' of urdu is completely different from mine, Muslims in India have somewhat combined the two to form a slang. Heavens forbid.
A silly characterization, especially when one considers the fact that Urdu isn't native to Pakistan at all, and there are in fact many times more primary Urdu speakers in India than in Pakistan. As far as the issue of the "blending" of Urdu and Hindi is concerned...I would argue that you'll rarely hear Urdu being spoken with proper grammar outside of Karachi. The Urdu I've heard being spoken by Pakistani Punjabis is filled with Punjabi words and grammatical constructs.
Urdu may enjoy far more official patronage in Pakistan, but I hardly think its fair to say it's a dying language in its native lands.