If I recall correctly from recent employee calls:

They like the 321Neo and want it, citing “good economics”. They said, however, that it’ll be “quite a while” before they can get their hands on them.

Also said not likely to order LR/XLR because “our seating config is quite dense” and apparently they couldn’t even carry the extra gas with such a heavy cabin config. Just what I heard on the call.

also. Frontier just dropped 17 new routes out of MCO today. Ouch