Past experiences with Chinese 'promises' of this kind have shown that they shouldn't be taken lightly.

In 'worst case', i.e. should Pakistan prove not able to fullfil its parts of the project, it's going to find itself 'invaded' by few thousands of very busy Chinese specialists.

Check all over Africa for countless examples from recent years (be these some road construction project in eastern DRC, so many others in Zimbabwe or Tanzania, or whatever other place).