In order to break this record, a player would have to get 200 hits, with 40 doubles, 5 triples and 40 home runs per season for 19 years.  Keep in mind that getting 80 extra base hits in a season is quite a feat.  Aaron did it only twice himself.  Ty Cobb never did it.  If a player had a 23-year career like Aaron, he'd have to average 164 hits, 27 doubles, 4 triples and 33 home runs per season to break this record.

Its a major accomplishment to achieve 4000 total bases in a career let alone 6856! Given Hammerin' Hank's tremendous talent, and long career, this record will be near impossible to beat!

I could at least conceive of someone breaking this. I checked where Bonds stands -- 5976 at present -- and I can't imagine him racking up another 900 anytime soon, but two mid-career players, Guerrero and Rodriguez, have already made it well past the halfway mark to Aaron. Both are 31 years old, and the latter especially has a good chance, though with the recent crackdown on illegal substances, it seems less likely.