I agree with afire.... It is entirely possible to build top quality guitars competitively priced in USA (C.F.Martin Co., Nazareth, PA, USA). The challenge would be the time required to establish a "well oiled machine" including a strong sense of teamwork and commitment at every level of the organization.
The article said that the Jackson line was co-located with the Jackson / Charvel / EVH custom shop. Makes sense that any Gretsch USA line would be co-located with that CS as well. I've never been to Corona so no idea how everything is set up there, but I would imagine that the USA line would cater to a select group of customers that are willing to pay near-CS pricing for a US built Gretsch. I don't see any threat to the current model there, especially in the next 5 years. The Gretsch offering can't be >$5k USA models followed by <$1k Korean models.
BUt on the other hand...
We love to knock Gibson, but they can do it too. sub-$2k Les Pauls still come off the line, up til last year, the LP Special Tribute was under a grand. Labor and materials are pretty much the same, building them here eliminates the slow boat to / fro China, and nullifies currency exchange issues. I could see something like a Jet being run through a big shop in larger numbers though, and sold for less than $3k. Gibson does it every day...