It wouldn’t be hard to re-edit.

As far as I remember -

Mustafar duel ends when the gantry collapses, Obi Wan rises to his feet on the lava bank, and just observes Anakin’s burnt crushed body under the gantry wreckage as he walks away.
Padme gives birth on Alderaan - but you only see one child.
Obi-Wan reluctantly takes the child (I think it was implied he was stealing him), and flies away into space in Grevious’ fighter.

And that’s it - open ended ending. It felt like an actual film, instead of a prequel spoon feeding the audience into IV.