Take a look at the data, I believe excess electricity is only temporary. Industry need much more electricity. China has a lot of excess power, but still building more and more power stations because it will be too late when you desperately need it.To be honest, Pakistan needs someone to buy the energy now so it can minimize its costs, and move on to the next projects.
China could also look at extending the transmission lines to Central Asia or even Russia, as a way to implement OBOR projects quicker.
From the data below, I believe more industry and higher consumption(household air conditioner) in Pakistan will need 10X more power in next 2 decades. The only problem is where you get those power. Hydro-power is the best power Pakistan can get so far. Pakistan has good condition for solar power as well.
Electricity Production in Pakistan decreased to 8677 Gigawatt-hour in December from 9327 Gigawatt-hour in November of 2019. Electricity Production in Pakistan averaged 8296.77 Gigawatt-hour from 2003 until 2019, reaching an all time high of 15790 Gigawatt-hour in August of 2018 and a record low...