Very sad news. Saw them twice back in the 80's. Both were great shows. I love their no BS approach. It would be almost impossible for them, IMO, to replace Malcolm, as it's been said he was the originator of most of their classic riffs and songs. They might get a different guitarist to fill in for a tour, but songwriting and album making? I doubt it.  
 
 
On a side note: a buddy of mine used to do backstage catering for some big concerts. Back in the day ('76 or '77 or so), AC/DC came to town, opening for Aerosmith. And he met both bands, and mentioned that Aerosmith were a bunch of SOB's and prima-donna's (mind you, to be fair, it was during their coked-up phase  

  ), but that AC/DC were the nicest, most down to earth guys he said he'd ever met in all his time working concerts. It seems to me that they've always maintained that attitude. Hope Malcolm finds some comfort.
P.S. - For what it's worth, he also met Ted Nugent once at one of those shows, and thought he was a total d-bag!  

  (just his opinion)
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