Just to clarify (as Photek is being rather confusing/wrong), the season pass will always contain the expansion; they're increasing the price of the season pass on Tuesday to account for the increased size of the thing.
Source:
http://www.vg247.com/2015/11/25/techlan ... ason-pass/If you're a day one owner, the season pass was rather a rip-off, as you got 2 of the 3 things included in it already. Your choice then, is to go with the season pass now and effectively get The Bozak Horde for free, or hold out and wait for a discount on the expansion some time in the future if you want to save some money.
If you don't have a Day One edition, the season pass is good value until Tues.