Personally I would lean towards replacing Russell - if Russell was the problem here. I don't think he is, because SX's low profile was a thing long before Adrenaline Mob came around. I think it's Romeo, or other guys in the band, and there is a reluctance to replace anybody in the band for fear of losing what makes them 'them' - or, perhaps, Symphony X simply is not a priority anymore (Jason Rullo has a food truck apparently??). It's a tragedy, these guys should've been on the road constantly over the years and should have released numerous albums after The Odyssey but we've only had 3 in 15 years...
Something's up and it just sucks. The quality of songwriting, of riffs, of singing, and the band just kind of lingers in limbo for years at a time... what a shame.