In long run, the infrastructure of Pakistan will be developed but Pakistan will be under huge debt. I don't think Pakistan economy will be big enough in future to pay back those loans to China. Also the money for transporting Chinese Good via Land and Gwadar will Not be sufficient enough to finish off these loans and this toll money alone cannot revive the economy. The dreams of creating economical/industrial zones will remain dreams. Thus CPEC will become one of the many lost dreams which pakistani nation has seen since 1947. But the blame goes to Corrupt Pakistani politicians who were corrupt to the core and on top, they were never visionary.
In future, the relationship between Pakistan and China will also cool down once China starts asking Pakistan to pay back their loans and Pakistan will not have money to return them. Then Pakistan has to give what Sri Lanka gave i.e. Ports and other assets.