The only way to get rid of the stators would be to use alternate counterrotating rotors....
Unfortunately that would require the same number of shafts as rotors, but as the cross section gets smaller with each stage, there would be enough space for a shaft in shaft in shaft in shaft .... design.
This would allow for a suprisingly short housing.
(and probably for a surprisingly short life as well)
Good luck, and stay away from the path of the high speed debris.