Wikipedia quoting Aviation Week says "Design changes announced in July, 2022 included an increase in the number of engines to 4 to allow for smaller less technically challenging engines and to allow takeoff at derated levels to lower noise; and redesigned gull form wing and fuselage to reduce drag." It's also acquired a Concorde-shaped wing since it was first designed. So that is a change in fuselage, wings and engines. In lots of ways they must be starting from scratch.
A technology demonstrator (with a delta wing, the former shape of fuselage and three engines) was rolled out in Oct 2020 and has yet to be taxied. When announced its first flight was scheduled for 2017.
I think the Boeing 7E7 was a much safer bet.