There will be hard pills to swallow for both populations but the long-term benefits will be for all its people.
Afghanistan's mineral richness could help kick-start a strong and robust economy with the human capital of Pakistan. The country would have strategic depth - a capital in Ghazni (also very symbolic) would be at least 500km away from any front the nation might face. The stupid conflict over the durand border would end etc.
Many problems to overcome. to name a few
1. Corruption must be eradicated from Pakistan
2. Afghanistan is much more religious (some policies towards education needs to change)
3. Would the Pakistani deep-state be willing to relocate the political and economic capital to Ghazni
4. Would Pakistan be willing to relocate majority of its strategic military assets to Bagram, Kandahar, Ghazni etc. (refueling aircrafts, AWACs, Nukes, transports). The heart of the country would shift westward.
Many challenges but alas they have to be overcome. I will at least work towards this when I return to Afghanistan in the next 3-5 years. Having Imran Khan leading Pakistan and Sirajuddin Haqqani leading Afghanistan would make it a lot easier.
1. Corruption is a problem all over the world, it's nothing special to Pakistan, there's just an unhealthy obsession. Anyhow, it's far worse in Afghanistan then Pakistan. Still it won't go away so I don't consider it as a factor.
2. that's for you to deal with.
3. The capital remains where it is. In my youth I thought it could be Kabul, but in maturity, anything west of Khyber pass is just too wild, so the capital stays.
4. Military assets will relocate according to need, if we're a single country then such things are not a conditionality, they work according to requirements.
Regarding the Pakistani nation. I don't think you Afghans realise how hospitable we have been.
I have seen Afghans in villages, with my eyes and on online videos, they're literally everywhere because every corner of Pakistan was opened for them. No one called them cockroaches, no riots to kick them out, check how other countries treat refugees and immigrant.
3-5 million over 50 years, that's what gets to me, it's still not appreciated how hospitable Pakistani nation has been, the Punjabis, Saraiki, Sindhi, Baluchi, Pashtun and Kashmiris, literary everyone.
The issue wont be Pakistani nation or the deep state. I assure you, all the issues lay west of the Khyber pass. Just being honest.