Remember William Carvalho? He's a Portuguese midfielder/defender who was pursued by Arsenal back in the heady days of the summer transfer window. He ended up staying at Sporting Lisbon, for a bunch of reasons -- but one of those reasons may be about to disappear.
According to Hutt crime lord Sepp Blatter, FIFA will ban the convoluted near-money-laundering-scheme that is third-party player ownership, a practice that while not wide-spread, is very inconvenient when it does pop up. TPO is, in short, when part of the rights to a player is owned by the player, his agent, or a separate company, rather than full ownership by the club at which they play. It throws a wrench into the works when a TPO player is involved in a possible transfer, mainly because it adds another variable to the already complex interplay between selling club, buying club, player, agent, media, fans, and everything else that goes into a player purchase.
It's not going to be an immediate blanket ban, though. According to Blatter TPO will not be banned immediately but after a "transitional period," which frankly could mean almost anything, considering the source. I'd bet that the most likely course of action is that there will be a freeze on any future TPO deals -- that is, outside entities will not be allowed to make rights purchases going forward -- but all players who currently have divided rights will remain in such a position until a sale is made.
Long story short, this is probably a mostly good thing going forward, but for Arsenal and Carvalho not a lot is likely to change. And even if the third-party was forced to relinquish his rights, his agent is still Jorge Mendes, so there's all that to deal with. Also you're not allowed to buy players in September, so.