I see Fitzy as a key forward, that is seen as a ruck due to him being 200cm tall, not because he's shown any ability to play in the ruck. As such I don't think he will ever be able to hold down first ruck, but be purely a relief ruckman.
Next year if Hogan, Dawes, and Clark are fit , and Clark is able to relieve in the ruck , I don't think you can fit fitzy in your best 22.
At the moment Fitzy is the only guy on our list that is not in our best 22, that has any trade value.
The big question of if you are going to trade Fitzy is if you believe Hogan will play most games next year, Dawes and Clark are going to able to get fit and stay on the park next year and in the future, and specifically if you think Clark will be able play second ruck .
If you think that will all happen you'd consider trading fitzy, personally I wouldn't bet on it and would keep him at least another year, though for the right deal I'd trade him.
Trading him for Savage isn't the right deal.