First of all,Iran is only connected to Turkmenistan in Central asia and Turkeministan already has other mean of access trade and having only a population of just 5Million.So the trade potential even by 3015 is less than 5Billion dollars.
Should i laugh?do you know that even prior to Chabahar,Afghanistan still had 30% of its trade supply through iran and is still having upto 30% of its trade supplies through iran from ports other than chabahar.
On the other hand,we have already secured Tajikistan as a potential for trade through Pakistan and have offered it to uzbekistan aswell and the rest of south asia.
Sign board on karakoram highway in tajik language
So you had trade with iran already from other ports and Afghanistan and even central asia potential trade with india in the next 50 years won't be more than 10Billion dollars.
Afghanistan 1/3rd of export is to Pakistan and 1/3rd of import agains is from Pakistan