This fact alone does not make the house worth less or when you go to re-sell it. The only potential drawback(other than unrepaired damage) when you go to resell is that since you will be obligated to disclose this information, just as the current owners are. Just like yourself, another potential buyer may be hesitant to sumbit an offer.
Although termites are without a doubt a major problem, you do have a few options. #1 I would ask if the current owners have a copy of any reports they received with the treatment. If the report mentions any damage be sure to ask what if anything was fixed that had been damaged.
Option #2 is to submit your offer and be sure to have contingencies in place that allow you to back out or renegotiate after you have your inspections. If you are working with a buyer agent this should be pretty common language in your offer form.
And then of course another option is option #3 walk away.
Good Luck and happy hunting,