Hmm, had a happy thought.
One big (& fun) difference between RoE and other BR, is the number of 'active vassals' - usually the vassals lurk below the RP radar.
However under the rules it makes far more sense to split realms up - the vassals then grant RP presumably.
Only the highest bloodlines would then have any major issue - and they just need lots of vassals pumping in the RP to keep themselves up if, for some reason, the individual wants a high bloodline.
As for retirement, I doubt anyone gives up power casually - most regent's probably only 'retire' when they fail a shuffle check or go completely loopy (in a socially unacceptable fashion, normal noble-style loopyness is of course fine).
Under ideal circumstances a handover would be gradual - Dad gives the heir a modest domain which lets junior get experience, meanwhile dad is funneling RP to junior as are other vassals, as junior's bloodline expands Dad keeps passing him more and more responsibility until junior hits their bloodline sweet spot and takes over everything leaving dad to retire to a single manor or suchlike.