- Lagrange points: I doubt it will be a feature in vanilla, as they have stated that with few exceptions, they're continuing with their standard 2-body physics calculations and using arbitrary SOI boundaries. However, I'm sure someone will create a N-body mod like Principia for ksp 2 at some point.
- Multiple Gravitational Influence: One of the exceptions to their 2-body system that they've revealed will be Rask & Rusk, two planets of equal(ish) mass orbiting on the border of each other's Roche limit in one of the new interstellar star systems. My guess is that they will have a singular SOI, that when entered, switches to pseudo-3-body physics temporarily.
- continuous acceleration and deceleration for short travel times: Already confirmed, I doubt they will be in from day one, but there are some far future technologies like the torch drive that are designed for precisely this. Secondly, in Lowne's latest video, Nate commented that the new manoeuvre tool is designed from the ground up to work properly with baristochrone trajectories.