What do you mean 'probably the end of Riot' if DiMeo left?

Riot have had 6 singers - Guy Speranza, Rhett Forrester, Harry Conklin, Tony Moore, Mike DiMeo, and Mike Tirelli - and have always carried on no matter who was on vocals.

Secondly, DiMeo has not been with Riot for a couple of years - he merely sang on their last 2 albums. Every gig Riot have done in the last 2 years was with Mike Tirelli singing because DiMeo was busy with the Lizards. The Lizards' bass player is a multi millionaire and can afford to pay guys like Rondinelli and DiMeo to go on the road - Mark Reale/Riot cannot.