Pakistan: no - they have way too many internal discord - considering that their north-west frontier province is actually a part of the Pashtun homeland that was torn apart during colonial times and that their western province of Baluchistan is also splitting the Baluchis (an Irani people) between Pakistan and Iran. I don't expect to see Pakistan survive until 2050 -- more likely a union between SIndh and West Punjab will survive.
Bangladesh - great potential, but we need to see. Right now they are battling extremists and extreme poverty.
A) There will be no USSR in the 2020 list.
B) There will only be one Germany which will be the biggest economy in Europe.
C) Countries like Russia, Ukraine, Belarus or Kazakhstan will pop up.
D) Some countries will do a complete 180 and turn their third world economies around among them being South Korea and Poland (related to the previous points).
E) Italy and Japan (two economic powerhouses in the 80s) will stagnate dramatically.
It's really impossible to predict the long term future. In 2050 China could dwarf all other countries or it could break up. The US could remain number 1 or it could completely crash. The EU could seize to exist or it could become the major power (with countries like Turkey and Ukraine joined and UK rejoined). All possible.
And Italy (possibly France, Germany and Spain but I think the former two would be able to ride it out) should the Eurozone be no more come 2050.
Italy has huge financial problems. That coupled with the refugee crisis, I expect it would drop off this list easily
But there is only so much oil money to go around. Its also likely that the demand for oil will be significantly lower by 2050 as gas-powered cars become rare or even banned - as is scheduled in the Netherlands.