The Demolisher seems to be the cousin of the Stryfe, which uses 4 AA batteries to power it's flywheels. The full-auto mechanism, which is that wide box above the trigger as seen with "Exhibit A", would probably fit in the Demolisher. However, with only AA batteries powering the blaster, unlike the C-cell batteries in the RapidStrike's system, it would lack the strength to power both the flywheels and the auto-pusher. The voltage would be there, but the mAh wouldn't be enough. AA batteries typically have 600-800 mAh each whereas C batteries typically have 8,000 mAh each.
I don't expect much to really change with what we've seen of the Demolisher so far. It lacks a name plate on the side of the blaster, so maybe some aesthetic things will change, but it's functions should remain mostly unchanged. We'll get more details later, as there's several months ahead left for more details to leak out.