If some research was done with respect to records that are currently more than two decades old and still going strong, there are probably 25-40 records that one could argue will NEVER be broken. Many of them have been mentioned here.
There is NO WAY a single record can be identified or proclaimed as "the one record" that will never be broken.
If someone wants to start a thread about records, call it
"Records that won't be broken in our lifetimes." That thread will get a lot of action.

EVERYBODY has a favorite record they want to nominate. I've got 3.
Example......Johnny Vander Meer's record of throwing two no-hitters on consecutive starts in 1938 will never be broken. It has stood for 84 years and will stand for another 84 years. in order to break the record, a pitcher would have to throw 3 consecutive no-hitters back-to-back-to back. That's not going to happen in today's era. Pitchers rarely pitch a complete game nowadays.