These are a lot of planes and I imagine more will be coming from other allies as they convert to the newer stealth fighters. By the time they get them a lot more Russian AA missile batteries and aviation will be destroyed. Russia might not have much of an airforce of obsolete planes by the time the Ukrainians have theirs's rebuilt with western equipment. There are an awful lot of ex-military C130 transports kicking around, and regulations prevent them from being converted to civilian use in Canada and the US and Ukraine could use a dozen of those too. I think the plan is to reduce the Russian air defenses and airforce before reequipping the Ukrainians. If they don't drive them out of Crimea this year, they will isolate them and use the F16s storm shadows, HIMARS and glide bombs to bomb the shit out of Crimea in the winter and spring of next year and drive the Russians to the borders on the mainland of Ukraine. By the end of this year the Russians should be in a lot more trouble than they are now with much of their AA defense gone, and their airforce reduced considerably.
Russia can't build many of the weapon's systems that are being lost in Ukraine, much of it is a legacy from the USSR and cold war. So destroy as much of their equipment as you can because it can't be replaced, and the threat is eliminated. Kill and capture as many mobiks as you can too and attack Moscow and other cities with drones in an effort to cause regime change and confusion in Russia. Ukraine is fighting for its life, and everything is on the table, you would be shocked at what any properly led liberal democracy will do to defend itself and still remain a liberal democracy when it is done, a stronger one in fact.