Not necessarily. You could have Rule by Blood if 45% of the power is with the Lords, and 45% with the King, after all. You certainly could have a current-style Democracy with the majority of the power sticking with non-landed nobles, but I couldn't come up with a good name (I don't like Democracy).
A bureaucracy?
Logged
“it was never wise for a ruler to eschew the trappings of power, for power itself flows in no small measure from such trappings.”
- George R.R. Martin ; Melisandre