A lot of Dems voted for Dubya in 2000, more than enough to forget about the ones who voted for Nader. The write-ins for Bernie won't have that sort of effect, they'll be ignored. They could give the GOP swing states, especially Florida. There are a lot of fucking morons in Florida who don't understand this. There is this widespread belief that they can write-in who ever they want to.
At least a Green vote makes the only party with a good platform gain traction. I will not vote Dem again, even faced with Trump, I just won't do it. I won't even do it if it is Bernie. I would vote for Bernie if he goes Green though. Stein would make a fine VP and they would keep his momentum and even draw tons of Dems into the GP. That's why I laugh when these Dems in denial call themselves independent. They're not independent, they are not even radical. They're just confused Democrats.