If a player's original drafter and/or major trainer goes bot, then the player will no longer play for any NT. This might require a little manual review as it could be difficult automating. Basically anyone could 'report' a given player, and then the action could be taken if a team that spent more than a few weeks training the palyer and/or the team that drafted him has quit playing BB...then remove him from the NT eligiblity/NT...anyone buying players off the list would know about this rule, so I think it would be fair.
in addition with this, no more FAs...if someone quits BB,the player they made should quit with them. FAs were necessary when the game was new and user numbers were growing...now user numbers are plumeting and there is an endless supply of well trained/supertrained vet players. No more FA.
Best suggestion you ever made!
But despite that I'd like to add something: if a player's leaving the game, all players, that ever played for or against his team, have to leave as well. They're retiring the same day. This would not only help all NTs all over the world, but it would make lucky fans a lot luckier, because they'd have much more chances of stepping onto the field and playing for their favourite team!