Dry Soup Mixes do eventually go bad but dry soup mixes can last for a long time when properly stored.
As for freshness the dry soup mixes last for around 24 months which is 2 years before it loses it's freshness but the dry soup remains safe to eat well past that time.
The expiration date on canned goods and dry soups and other dry foods is just a general guideline and means that the dry soup mix or other dry foods as well as any canned food remains fresh up until the expiration date.
There's no need to throw out foods just because of the expiration date because most foods such as dry soup mixes, other dry foods, canned foods etc all remain safe well past the expiration date.
It's best to eat the dry soup mix before the expiration date for the best taste but it remains safe to eat past the expiration date.