Sell the email routing
There is one thing of value that yahoo have, and unfortunately for me, I'm one of those affected. There was a time when the internet was coming in, and I was about 16, when it seemed a good idea to grab a yahoo email address. That account is now the username to so many services that it would be a major ball ache to try to untangle myself from it. I've got my own domain now, but I think I'd probably be ok to pay a small subscription amount to route email to that, rather than change everything to directly hit it (where it's even possible to change it).
I don't think I'm the only one affected, so there's money to be made there...