I really doubt that considering Immolation is one of the most early death metal bands. Dawn of Possession,etc... are old school death metal nor does the band focus on being brutal and more on heavyness and weird rythmn.
Suffocation is an old school death metal band. Human Waste is old school death metal borderline thrash and effigy of the forgotten is an old school death metal album, it's brutal, but I would think that term is already in the term 'death metal'.
Something like suffocation or immolation is not any more brutal extreme or heavy than say Bloodbath.
anthrax is the one who did the song with public enemy right? so a numetal vocalist oesnt seem like a stretch for these guys. i use to listen to slipknot, they never had any real gutteral vocals or anything but, well, i dont know that is intresting. he just needs to stay the fuck away from slayer or kreator, thats when i will start having a problem with it.
unlike some others who seem happy to just argue i think that anthrax 's best is long behind them and after their recent new split after reforming the original lineup i dont think they will ever return to their heyday of AMONG THE LIVING OR STATE OF EUPHORIA PERSISTENCE OF TIME ever again