Luckily for us in Mt. Shasta right now the smoke isn't going toward the Mountain of Mt. Shasta or the city but towards the ocean instead. So, after visiting friends I didn't see any smoke at all to the east of Castle Lake which is good news for at least the Mt. Shasta Area.
This news I'm not sure about but it says that it might go to Lake Siskiyou. I'm not sure about this website whether it is valid or not but this is the fear of Locals in Mt. Shasta that it burns to Lake Siskiyou. However, I don't think it could make it to the city of Mt. Shasta because it would have to cross Interstate 5 to get there.
However, it might all depend upon just how many people are fighting it and so it's likely about resources and the winds more than anything else.