I wouldn't get caught up in arguments over 4 years vs. 6 years. The point is that most of us agree Kwiatkoski's gonna get a multi-year starting deal over Trevathan.
Absolutely. Both Trevathan and Kwiatkoski are going to look for starting roles next year, and to be paid like it. So unless you are only offering a one year contract, it makes better money sense to spend on the younger player.
At the same time, you have to consider roster spots in how you resign players. KPL looks like a good depth player, and Iggy is barely being paid to be a #4/ST guy. So it wouldn't seem likely that we'd resign both ILBs.
With those two points under consideration, I think it likely that Trevathan is playing elsewhere next year, and Kwiatkoski gets at least a 3 year deal to stay.