Those who blame Comey alone are not going to change their minds. They will continue identify him as personifying the reason Clinton lost. This is based upon an emotional pathway in their brains since 2016, rather than an accurate, rational understanding of the synergy of events from that time. This is frequently illustrated in some of them demanding that Comey should have evened things out by saying the FBI was investigating the felon -- though they were not, until Comey was fired six months after the election.
I'm not opposed to emotions. I suspect that I once experienced one, until life beat it out of me as a child. (grin) I do recognize that this is a stressful period, and that emotionally-driven Democrats will cast their votes for our candidates as a result. However, our party needs non-emotional people to be the rational foundation for campaigns, identifying past errors to be sure we do not repeat them. After all, it was none other than Ben Franklin who said, "When passions drive, let reason hold the reins." I doubt that even old Ben could change people's minds on Comey.