That depends on what you consider the chassis to consist of. Things we know are being talked about changing that could be seen as part of the chassis include:
- The effect of Nat 1s and Nat 20s
- The weapons table
- The way skills work
- The way the Dash action works (from double your speed to a bonus move)
- The way difficult terrain works (or what it is)
- The way Exhausted works
- Grappling
- The way the Help/Assist works as an action
- Inspiration/"Heroic Inspiration"
- Hiding - Hidden is not a condition in 5e but is in One D&D
- The Influence action
- Invisibility
- Jumping (it's now an action)
- Light weapons and two weapon fighting
- Interrupting rests
- Search and study actions
Calling it "the exact same chassis" is overstating things. It's certainly a different version number even if the same model. And at that point it could go either way. (I come down on the same side of the fence you do based on what I've seen so far but that doesn't mean that it will necessarily go that way).