You're just clinging to definition while missing the actual issue.
For the 737 to compete with the A320neo, it required much larger engines.
For those engines to fit, they'd either have to raise the landing gear and redesign the airframe to accommodate the changes (which would be a very different airframe), or they'd have to offset the engines (which massively increases the stall risk and lead to the MAX disaster).
This is not an integration issue. There is no possible way for the 737 to fulfill the needs of the 21st century without becoming an entirely different plane.
For the 737 to compete with the A320neo, it required much larger engines.
For those engines to fit, they'd either have to raise the landing gear and redesign the airframe to accommodate the changes (which would be a very different airframe), or they'd have to offset the engines (which massively increases the stall risk and lead to the MAX disaster).
This is not an integration issue. There is no possible way for the 737 to fulfill the needs of the 21st century without becoming an entirely different plane.