There's a problem with integrating F-35 to JSE and with that declaring Milestone C. Also, it seems to be (ie. imo) that the higher ups of the pentagon are willing to wait for block 4 and possibly the new engine before reaching FRP. Though on long term Pentagon and LM plans to ramp up to 220 airframes per year, or in other words around 80 airframes more than what LM currently manufactures, which I think would be the case of mid 2020s. There were also reports that the current rate of production will be kept "for a while" as well.It seems unlikely that KF-21 gets delivered much sooner than an F-35 order. Has the F-35 officially passed into full rate production yet?
Had written about it a while ago if you're interested : https://www.secretprojects.co.uk/th...-35-news-only-topic.17732/page-67#post-490497
There are other articles by AF Mag from last year regarding it, too.