I think Salty said the extend and trade scenario is impossible, not the general George + Hayward scenario, which is certainly possible. Granted, he also has said that it's virtually impossible to happen due to cap and luxury tax implications.
I, respectfully, disagree. There seems to be quite a bit of smoke about Danny wanting to pair a star free agent (Griffin or, more likely, Hayward) with a George trade coming after the fact, and the timing seems to suggest this, too. And that kind of swing/wing heavy lineup seems right up Brad's alley - IT, Brown, Hayward, George, and Horford with Rozier, Smart, Green, Tatum, and Zizic off the bench.
But I don't think it's as farfetched as some make it out to be. If Danny plays his cards right, we could only be carrying 4 max or near-max contracts for two years, surrounded mostly by high-level rookie scale contracts in Brown, Zizic, Tatum, 2018 Brooklyn pick, etc. and ring-chasing vets on minimum or smaller deals. That's certainly doable, especially by our owners who have been willing to pay for a winner in the past. Also, by controlling the timing, it still should be possible to avoid the repeater tax down the line.
The real problem would be when Brown, Tatum, and the others are up for new contracts, which would be right about when PG, Hayward, and Al are up, too, meaning that would force us to pick and choose who to keep.
So, I mean, like any big trade, it's unlikely that everything falls in line just right to make it work, but it's certainly not as impossible as many are making it seem. I think the owners are agreeable if Danny could pull it off.
EDIT: And this is all assuming that we max IT out, too, which I think is far from a certainty in this scenario with two big scorers in George and Hayward, let alone his injury that could limit him and decrease his cost next year. I mean, honestly, I really hate the fit of IT with that hypothetical lineup anyways.