No one pushes you to buy Chinese weapons, and the cooperation between China and Pakistan is win-win.
Pakistan can buy Su-35, Mig-35, Su-57, S-400, and so on from Russia at any time.
Without the orders of FC-1/JF-17, Type 054A/P, and so on from Pakistan, it is still fine to China, as China's military industry can get enough orders from PLA.
China just provides one more option to Pakistan, and Pakistan just chooses what Pakistan needs. That's all.
If other countries can provide better choices, I don't think Pakistan would refuse.