Your 25 year old account might not drop off after 10 years. Sometimes they do and sometimes you can get lucky. My wife still has a J C Penney CC that was opened in 1987 and closed in 1990 on her reports. Her scores benefit greatly from this because her next oldest account is only about 10 years old.
The key word in the above post though is "lucky." That's great for AoOA that the account referenced above is still sticking around, but that's the exception and not the rule. The expectation should always been that a closed account is going to fall off after roughly 10 years. If that expectation is exceeded, great, but it is indeed rare.