Recent Polish procurement seems to indicate that they are buying items that can be delivered as quickly as possible. New F-16s and F-35s have long production times due to the amount on order already. The F-15 line is shorter and the US would let Poland take some of its slots. The Poles should probably sign before the Indonesians do, though. The only thing that makes sense if this goes through would be for Poland to have a future fleet of F-35s, F-15s, and low-end FA-50s. F-16s would be gradually donated to Ukraine as replacements come in. But this is Poland we're talking about, so anything is possible.