Following the line of thought begun may moving the creation of levies over to manor holdings; manor holdings now take over the role of law holdings in terms of providing access to the manpower needed to muster units.
No other changes; just replace 'law' with 'manor'.
It should not greatly affect any rulers.
(in a later age when cities become even more important guilds might take on the same role - a subject that interests me greatly - but that is for later)