Becoming a key because it’s the first meeting of Captain America’s and is also a homage cover of Captain America #199. Captain America #28 vol4 is silently becoming a ghost and can still be found in back issue dollar bins or online for $10.
Its not a key. By the end of FATWS the book will be forgotten and plummet in value.
They have to create spin-offs for next years shows they can’t keep paying their movie stars to do tv shows. Cap traveling in time has been kicked around for a show or movie.