What is the stability of a 777-like plane if the engines flameout and the autopilot disconnects and the pilots don't make any inputs?
Assuming CG is within limits, the plane is straight, level, and both engines flame out simultaneously, lacking any control inputs, the plane will dive until it reaches its elevator trim speed, then glide at that speed until it impacts.  As the directional and roll stability would be fairly good with the 777, without variable cross wind effects or any other yawing tendencies, it would probably be a straight in crash.

This scenario could be tested under controlled conditions.