I don't accept this for a second. We would still have Trengove - he committed to the Dees early, and it was genuine. He appears to have a much different approach to the club, his team mates and perhaps to his career/life goals to Scully.
The underlying character of the player is very important in this debate. It's not all about the dough for many - in fact, for some it's not about the dough at all.
Many, many much better and more established players than Scully were targeted by GWS, and they all stuck fat with their respective clubs and by their team mates. They didn't run for the cash - other factors were too important to them. For many, it seems they didn't even really entertain the offers from GWS. It was just not an option.
And I think it is bordering on slanderous to suggest Trengove may have gone to GWS if he had been targeted (I know that's not what you intended Kick It Long, but IMO it can't even be suggested re: Trengove). He strikes as a young man of extreme integrity. For instance, without being pressured, he approached the club after the 186 point humiliation to Geelong and essentially said, "I am committed to this club - sign me up forever". And that's in the context that he's a young AFL gun in demand and his club, at the time, was completely imploding. Character in spades - he wouldn't leave the trench.