LBJ did sign Civil Rights into law in 1964 and 1965, most American history books mention this, I believe. I don't see where he "made it sound" like anything other than what you are projecting into his remarks. He didn't SAY that CR was bad for the nation, he specifically indicated how it was bad for the democrat party, and that was what he was talking about, not the nation. I personally think he picked a poor analogy, and I don't know that I totally agree with his point, even in the context he made it. I see what he is saying, and I do think this will certainly have a damaging effect to the democratic party in the near-term elections, and in that regard, it might be a similar political outcome as democrats experienced through passage of civil rights. Look beyond the "rightness/wrongness" aspect, and realize he was not referring to that, and you will see what he was actually saying is different.
Like Civil Rights, this was painted as an issue larger than politics, and based on principle. Despite strong rifts in the democrat party, the leadership pushed for "doing the right thing" over "doing the popular thing" and it will have a political cost. Where I depart from Newt on this, is that I don't think it has a long-term effect on the party, certainly not 40 years worth. I think, beginning in 2010, you will see Democrats claiming Republicans "want to take away your health care!" They will get a LOT of emotional mileage from that!