To be honest attempts to replace short to medium range triad of M163 Vulcan, MIM-72 Chaparral and MIM-23 Hawk in the US armed forces has been a shambles over the years!

Just look at the list of systems that have either failed, rejected or adopted only to be later rejected!

Going through the list you get everything from, loss of interest, budget cuts, incompetence, bad design to “Not designed here” syndrome!