Yes, they can still sue. I am going through this right now. The original creditors charged off my credit cards back in 2004, sold the accounts in 2005, and I am now being sued by 2 out of 5. I believe the creditor can only sue you up to four years after the debt occured but this timeframe starts over any time the account is updated by you or sold to another company. I was told to not acknowledge the account or talk about it with the creditors to stop the account from being updated, but that got me nowhere since they sold it anyway.
If an account has been on your credit report for more than six years, you can dispute it and have it removed. They should give you the approximate date it will be removed right on the report for each account. Just a little tip to clean it up later! Good luck to you and me! lol.