Yeah, they said it over a week ago already. Delete. Delete your saves, too.
Well, they said we could, that the new files wouldn't be similar enough to the old ones or something.  I recall that.
I think the issue is that some of us really don't know what we're doing.  For instance, I have no idea if Steam will automatically start the update for me or the new install for me or whatever.  If it won't, do I need to be hovering by my computer at the appointed time?  If it does, do I have to open Steam or is Steam always running in the background?  
*
I'm not expecting answers to those questions.  I'm sure I'll figure everything out as time moves forward.  I just wanted to mention it to show that some of us are a bit uncertain about how to proceed.  Getting a community update is always nice and helpful for dummies like me.