I wonder who he'd gravitate towards?
I agree, though, that the modeling now is so good that going all-digital is finally a viable option. I use BIAS Amp and BIAS FX from Positive Grid and they're awesome. What's really cool is I can take my tones anywhere and I don't need anything but my iPhone and my bluetooth pedalboard to switch between amp settings for clean/distortion/lead that's it. Plug me into the PA or board and I'm good to go, I don't even need to bring an amplifier with me to gigs now.
I could imagine Petrucci forging a relationship with a company like Positive Grid or maybe Boss - any company, really, who makes a "smart amp" those are definitely the wave of the future. I think straight up tube amps will always have their place, no doubt, but man, once I tried BIAS Amp I was hooked. It's got everything you could possibly ever need from Marshall 100 Watt full stacks to tweed combos, fender twin reverbs, you name it. And the tones are indistinguishable from the amps they're simulating, assuming you have access to a quality board/pa/house system. I keep an old 60watt Roland Cube in my trunk just in case, but I haven't needed it in years.