I'd guess not this sale, but maybe Christmas. No guarantee though. Usually the Daily Deals and Flash Sales will be repeated, but not increased. The other "hidden sales" (i.e. Skyrim is currently 33% off) have a decent chance of having an increased sale later on. If past is any indication, the last day usually has all the Daily Deals/Flash Sales on sale again, so you can always wait til the 27th, but again, there is no actual promise that Steam will do that, just going off of past sales