I still think Fowler has to maintain his great start for me to conclude that he's a top pairing defenseman. He absolutely is playing like one right now, but he's had streaks like this before.
With that said, a lot of this could be due to who he is paired with. Bieksa is awful, and he brings down whoever he plays with (last night it was Theodore). Bieksa was playing 20+ minutes a night last year with Fowler when he should have been playing, at most, 15 minutes. On the other hand, the Fowler-Manson pairing has looked great. I hope they keep it up.
As for the proposal, this deal doesn't incentivize the Ducks enough to move him before they really see what Fowler's capable of. They would be foolish to move him right now, unless they received an offer that they couldn't refuse. Theodore obviously isn't ready to step into his role. Plus, Fowler is on a cheap deal for a top 4 defenseman.