Interesting, Both links still work for me. If you wish to get technical, the word bretherin is also 100's of years old, 3 different spellings have been used over the ages and these days , "Brethren" is more commonly associated with religious cults and or organisations, leaving Bretheren and Bretherin and since Bretherin has been adopted by a current group in modern society then i would suggest that Bretherin would be more suitable....
So, essentially, what you're saying Mick, is that slang words created by illiterate street gang members now take precedent over words created in the English language hundreds of years ago? Seriously? 
Actually, {although no where does it mention "gang members"}, Yes, as all language is evolving and will continue to evolve, most of our "English" words have their roots in Latin, French, Hebrew, Greek, yada, yada, yada, do i need to go on....
If you don't believe that our language is evolving, look at current updates to the dictionary {any or all}....
Some are just plain stupid....
Interesting statement on a mainly American forum as well ....
