As stated, Buck's traditional USA knives, both folding and straight, do well with 420HC. However, there have been a slight few special runs using "super" steels. Noteworthy, especially, in 110/112s, Alpha folders and a few special run long knives. They have dabbled in 154CM, BG-42 and ATS34, again usually not in traditional folders. Recently, some non110/112 lockback Bucks have been produced in S30V and two Sandivic steels. One run of the 118 small straight skinners in D2 even.
Were I to ascertain a wild guess even about the future, the possibility of a SS traditional folder it would likely be limited to S30V or the Sandivic's.
At the moment no 300 series is outside of the 420HC world, except for the special order Buck USA Canoe sold by AG Russell.
Yes, Santa Claus I would like a S30V Warcliff blade replacing a secondary blade in 300 series stockman and jacks. But not holding my breath. A Dami clip blade would cause me to split my breeches.....
300Bucks