Possible to change obsolete "Yahoo! Mail" address by creating new ID?

You can create as many Yahoo mail addresses as you like, but if you want to keep your points from your current YA account, you should create a separate mail address with a Non-Yahoo provider. That is necessary so Yahoo can mail you a temporary pword in case anything goes wrong. Then go to your profile, click "edit my info", scroll down to "email", under "use another email address" click "add an email address", enter your new mail address which is not registered with Yahoo, click "preview" at the bottom and then "okay". From now on Yahoo will use your new address for all communications with you. When I signed up with YC (that's the German YA site), I didn't have a Yahoo mail account, never got one either, and I never encountered any problems...:-)