I'm not sure what Xfinity means. "Formerly infinite," perhaps?
Such so-called rebrands cost money. New signs, letterhead, business cards, vehicle IDs, etc., etc., are but the iceberg's tip. The real expense comes in retraining the masses to recognize you by, and trust you in association with, the new name.
Which leads me wonder: what marketing problem does this so-called rebrand solve for Comcast?
I refer to this as a "so-called" rebrand because a new name and logo do not a brand make. Those are marks. Brands are bigger and go deeper. (I deal with this extensively in my book.)