What that sentence means is that only members of the current LNC can _serve_ (that's not the same as "be elected" ) as the next National Chair, and the current LNC (or perhaps its successor) are the only people who can supply the National Chair through the year 2014. Ernie Hancock, who is running for National Chair this time, appears to have worked out a great advantage he has relative to past years: He will be running against the incumbent. His disadvantage, if you note the tense of "has served", is that if this Bylaw passes he will be unable to serve as National Chair, even if he is elected.I don't see how Phillies can read the rule that way, unless he's saying that every living alumnus of the LNC who served before Nov 2004 is also currently an LNC member -- which I find very hard to believe.
Scott Lieberman points out on the BylawsCom blog that it's somewhat vague whether "member" includes alternates. I would guess not.
The anti-takeover intent of the rule is good, but I don't see the point of requiring LNC tenure farther back than the previous term, and the qualifying positions might be expanded to include, say, state chairs. The more interesting anti-takeover proposal is the one to lengthen Judicial Committee terms to 14 years and stagger them so the whole committee never turns over at once. The core idea of avoiding complete turnover is a good one, but 14 years seems too long, and there should be some way for a super-majority of NatCon delegates to prematurely terminate a JudCom member. Maybe the margin of victory needed to defeat a JudCom incumbent could be proportional to the time left in her term?