The roof:direction key is indeed the standard choice now, and there’s no longer a reason to use any of the older tags today. It’s the most commonly used one, too.
Do you mean automatically replacing the tags in the database? I’m not aware of any plans to do that. It would be possible, of course, and I would be ok with it as long as the guidelines for automated edits are followed.
Thanks for the info, Tordanik. Yes I meant auto edit all other tags. So maybe I can get the ball rolling 
@Tordanik: as I can see do you work for OSM2World. In TagInfo I read about the “roof:ridge:direction” is used by this project. In tag mailing list, we think about editing the “roof:ridge:direction” too, so wanted to ask if OSM2world can deal with a 90° rotated “roof:direction” tag for double sloped roofs. So we can change this tag too. Thanks ;D
That change wouldn’t be a problem for OSM2World. In fact, OSM2World already uses the same code for both roof:ridge:direction and roof:direction anyway, just with a 90° rotation beforehand.
Good news!