I am flummoxed to see lack of consensus on this key issue here.
Backgrounder: There is a great deal to say about this "Belt and Road" (BAR) / CPEC. This is Pakistan’s Suez Canal and more. This mammoth undertaking requires detailed analysis - perhaps another day
. Within Pakistan there is a storm in a teacup regarding the initial route using the motorway. This seems to reflect lack of understanding/experience regarding mega infrastructure projects and their second and third order effects that ripple through economic food chain. The need of the hour is for Pakistan to continue implementing the project systematically and let the Business World know it is happening on schedule. In order to go about it swiftly, it makes perfect sense to initially make use of infrastructure already in place, i.e. the Motorway project(M2,3,4,5). If the predictions are realized, a single 6-lane highway will get clogged with Transnational, long-haul, high-speed, time-sensitive freight (TEU) being carried by heavy-duty freightliner Semis (what you guys call lorries but bigger). This may cause friction between TransPak and local traffic. There will be accidents, legal implications, pilferage and corruption leading to complaints from Chinese businesses. Once tonnage exceeds 15 million TEU, China will most likely request Pakistan to plan a dedicated expressway for TransPak freight/commercial traffic destined for Urumqi and points North/North-East…even Chengdu!! I anticipate that to happen by 2022-25. They may also ask you to make it a "Right-hand" side traffic flow, make the design more Euro-Chinese for speed and other specs. Perhaps Pakistan should study changing over from colonial legacy road specs to more integrated with Berlin-Beijing design standards. It will be easier to do at the very outset then later on. In any case, Pakistan is going to need at least one more North-South Highway.
Coming to the issue of land link with Tajikistan: why would Pakistan want to forgo a strategically pivotal Bypass? Does Pakistan want to be a one-act play only? Because this will create a choke-point in the Northern Pakistan where the famed KKH is vulnerable to bad weather, earthquakes, rock & landslides, floods, local politics, unforseen mischief from unknown (sic) sources! Anyone who has crossed Swiss-Italian borders in the Alps (E62 Lausanne-Simplon Pass-Milan) knows that a backed up lines of trucks for tens of miles is bad for time-sensitive cargo. What if the problem lasts for over 48-72 hours. In International business time that is an eternity. Without options, all flow will stop and ripple back to Gwadar port operations and beyond. Pakistan will be getting complaints from global shippers, insurers, and their clients. Trust me that is worse than thinktankers, journalists, diplomats pestering you about security issues these days. That would be "REAL" bad press and justifiably so.
Ergo Pakistan must not put all her eggs in the Karakorum basket. Please take my advice and create "OPTIONS" for yourselves. That is where the Lowari-Chitral-Durah/Dilisang/Broghil Pass-Eshkashem-Dushanbe becomes relevant. Sarhad-Broghil to Ishkoshim is jeepable so basically Pakistan has to lay asphalt right upto Broghil on their turf. Also part of Wakhan can be traversed via tunnel to hedge against inclement elements. It is feasible and already studied in a prelim. Considering the strategic import of TransOxus, it behoves Pakistan to begin laying facts on the ground for a favorable future….l will leave it at that for now! This Chitral Bypass/Spur will enable all traffic to reenter China at Tajik-Chinese border via Eshkashem-Khorog-Murghab-Kulmar Pass (M41; 300m). That is already open to some traffic. Two major Tajik trucking companies SorbonoTrans &Tojiron have 40-25 ton trucks ready to use this route. Once there is a completed link available it will be hard for Afghan authorities to block at least Tajik two-way transport to Gwadar. You can build on that later.
BTW, the Kabul-Salang-Balkh-Termez has many, many problems, trust me on this!
There are many ‘protagonists’ to negotiate with, and Salang is a major choke point in many ways. It can be a tertiary option that will only mature whence TAPI is in play. One last tip: Pakistan will find it much easier to work with Tajikistan than Uzbekistan. And Eastern Tajikistan, Wakhan, Northern Chitral has a Wakhi ethnic dispersion which helps. They are all the same peoples.
Cheers.