Unless they're thoroughly infested and the termites have eaten out their foundation. Then they're best to be disposed of.
What's wrong with a 3rd party? If the 2-party system is so great, why didn't the Founding Fathers just write it into the Constitution?
Nothing inherently wrong with a 3rd party, with the small exception of human nature. We tend to be dualistic; the third parties usually get single-issue persons, or those who are at the far ends of the political Bell curve.
And if the existing parties are so rotten, then infiltrating and taking them over will be remarkably easy.
Your complaint is that it's really too much work.