Let me see if I can tackle them all, though not necessarily in order. First, on the question of motivating discouraged voters. What I am arguing is that there is the real potential to mobilize a significant number of people who otherwise wouldn't bother voting for Gore or Bush, and while this potential will first and foremost help to establish the Greens as a national force, it may also help a great many Democratic congressional candidates down ballot. Populist truth-tellers within the major parties have also had the same effect, for reasons that I think are similar. My friends in New York's Working Families Party can point to several local races where they have boosted turnout of both base voters and occasional voters to a dramatic degree.
Old brands do eventually go stale, and can collapse if people discover new ones.
Now to your questions about Nader pushing the Democrats to the left. I hope you do too. Such a coalition would lead with a national living wage as its banner, and it would fight for starting-gate equality for children, universal health care, and substantial investments in housing and the environment. I do think such a coalition is possible, and that a strong Nader candidacy may help get us there. Part of the problem with the national Democrats today is they only drift to the right, responding to Republican pressures and the allures of more financing from big business.