Frankly, I hope the band's relations with John haven't shattered and that he'll come back if they ask him.
I never was in favor of the reunion tour, but now that the 'fad' is over, they apparently have no clue where to go from here. I think they had set their hopes on Joey fully rejoining and never really thought he would say no to a full reunion in the end.
If John quits as well, I'd say this band is as good as dead.
I found John perfect for the band and he (either directly or not) managed to change the band's sound and image for the better. WCFYA was the first real album that got Anthrax back in the spotlight again and I truly hoped that it would only get better from there. Plus, I've been a fan of the Bush-era more than the Belladonna-era, so if the worst would come to pass, the blow would be even harder for me.
But, I guess only time will tell...