I'm guessing this particular items is a glitch rather than a sign the flights are being pulled. It's just 12/23 through 12/26 that show "classic-only" availability on MKE-MCO, and return flights MCO-MKE show all three fare types. From 12/27 onward all three fare buckets are available.

Of course that doesn't ensure MKE-MCO won't see changes (though it would be odd for a cut to start 12/23), and the detective method blue used is indeed often a useful one to get early information. It worked on the drop of DEN-LGB a couple of days before it was officially pulled, though it didn't work for MKE-RDU...I checked those on Friday and saw all fares available, and early Sunday morning they were pulled.


For LAX I would not hesitate at all, because (1) you'll be booking a connecting or 1-stop flight anyway, and (2) even if there are schedule changes to your particular flight, Frontier will have several alternate options to get you there.

For MCO, there is a slightly greater risk because if your nonstop flight is pulled, you could find yourself connecting in Denver or being re-routed onto United, American or someone else. There is always this sort of chance no matter who you book, especially when it's several months out. And with fuel prices so high, several airlines (not only Frontier) have signaled that fall cutbacks are coming, so anything on anyone you book for fall could be affected. The difference with Frontier is that they don't have as many alternate options on MKE-MCO as they do on MKE-LAX.