We don't get the F-35 numbers that we want.
We extend the more affordable and proven F-18 line to fill the gap.
As is likely - UCAV-N underperforms the hype and is used as what it really is - a recallable, reusable Tactical TLAM. Something that is useful in only the most permissive and ideal environments. Worse than the classic TLAM - the UCAV-N will be exceptionally fragile in the the EM spectrum it desires to operate in from both a defensive and offensive perspective.
As a result - what do we face the rest of the word with for Fleet Air Defense when the USAF cannot spare its F-22 coverage?
Well - you go to war in 2025 with the F-18E/F - an improved 1970s era strike fighter. Very good if it fights in the vignettes that favor it. In the face of what it might have to actually engage in combat against? Well ....
Let's see what our friends in Australia have come up with in their ponderings.

The Buffalo II?