As a player that has been playing since the start of beta I consider myself fairly conservative in the amount of cores I have compared to many other long term players. I've accumulated multiple bases, a few player ran shops, space stations, and a few dozen ships. I also run quite a few mining I am also apart of a few orgs that have very large projects (cities that are well over 200 cores). Most players that have been playing for more than a few months utilize a personal org where they are the Super Legate and have trained the talents to expand the amount of constructs they can have. Simply put the current limit of 17 personal slots is far too low. With the latest patch of Mining Units and those each requiring a core to mine I am well beyond what the proposed changes will allow even designating 100% of my allotted slots to my personal org and have none to donate to other orgs. This also includes the cores from my 1 alt account as well which would bring my total allotted cores to 74. At this point I would not only have to reduce the amount of cores I own currently, but would prevent me as a player progressing further in the game. I believe that player contribution to an org could be a step in the right direction, but there should be a baseline of construct slots that an org has that can be increased through means of contributing players, but not at the cost of limiting that player.
I completely understand that nesting orgs are a problem that need to be addressed. Currently, with T5 talents an org tops out at 275 constructs, and can essentially have infinite sub orgs resulting in there being no limit. First and foremost this need to be corrected instead of implementing a fix that will negatively effect all players, instead of just those that are abusing the current system. I believe a good way of doing this without eliminating sub orgs would be to make it so that Orgs that have another Org as a Super Legate are either not given any constructs by default, or given a very small amount.