Losing Su-27s is a tough blow for Ukraine since these fighters offer unique air defense and interception capabilities that are hard to replace, even with modern Western jets like the F-16.
While the F-16 comes with modern avionics, it’s fundamentally doesn’t directly replace the specialized air superiority role of Su-27.
Swapping Su-27s for F-16s would mean Ukraine sacrifices some strategic advantages of the Su-27’s longer range and heavy payload, even though the F-16 brings cutting-edge technology and interoperability.