Ok, I also tried heating up the freehub....no success.
Finally, I used a 3-arm gear puller that I use to pull crankshaft pullies off V8s. I put the 3 smallest cogs on the freehub to give the tool something to grip, and a small dime sized washer sat on the end of the 15mm axle for the puller to push against. Came off (with some force) in seconds. Freaking insane.
The old freehub and the hub internals all look fine, so I simply cleaned them up and re-greased the hub. The 11speed freehub slid right on, altho I don't even want to know if it slides back off. That'll be a surprise for another day.
This is similar to the tool I had to use:
PS, my older PRO+ powertap freehub still slides off as easy as it did on day 1. Not sure whats up with this G3.