I've been thinking about this and honestly, they don't need a new singer. Mike can handle vocals just fine, especially if he gets a vocal coach. However, i would like to see them bring a touring instrumentalist on stage to take over some of Mike's instrumental parts so he can focus on vocals. It's way harder to sing at 100% while playing an instrument at the same time. I mean, it's not impossible as there are a lot of artists that sing and play an instrument live but it does help being able to focus on one thing at a time. I remember when they did their show in amsterdam this year and Chester was playing guitar during Sharp Edges he jokingly said this after: "Man, it's hard to sing and play the guitar at the same time."