That pot you're smoking must be really top tier man, where'd you get it? :p
Afghanistan will split up, The Pashtuns will either join Pakistan, or will have thier own state, the Hazaras will have their state, the Tajiks will go to Tajikistan, and Uzbeks to Uzbekistan. Even once this happens, there still won't be peace, instead perhaps more wars. Pakistan can't expand like that, unless another Zia-ul-Haq or Saddam Hussein comes to power in Pakistan. No other way for peace there, besides nuking the place till it turns into the "Afghan sea", we might even have to include Balochistan and NWFP to really have peace though. Plus, I'm sure Pakistan has some problems that she needs to fix, before appointing a pothead like Nawaz the PM of fairly prosperous post-soviet states who hate our guts.
oh, Post scriptum:
The last thing any sane person would want is to arm 3 million uneducated fools who've probably seen their family members die in front of them thanks to the AfghanTaliban, but are yet pro-Pakistani Taliban with weapons, unless you have 12 million troops ready or want them to take over Pakistan and start nuking places at random.