Yeah I think the worst case scenario for Sword Oath (where Det stops affecting it) is simply that Paladins will switch to stacking Crit rather than Det if they want to max out their DPS (or heck, even skill speed, we don't know the numbers yet). The DPS numbers of the new paladin skills look so good that I'm sure our overall damage wont be non-competitive, it just might mean we don't view Determination as the only secondary stat worth stacking now.

Let's face it, in 2.0 Skillspeed, Parry and even Crit were pretty much worthless to a paladin in the grand scheme. Det and Acc were all you wanted, and Crit was a tiny boost that was "better than the alternatives". Hopefully the changes will make gearing more interesting so Crit, Skillspeed and Det all have similar effects on our DPS so those terrible Skillspeed/Acc tanking items wont feel so awful.

(Still hoping Parry becomes a viable stat to stack though, much as I entered into the "stack DPS stats" philosophy in 2.0 I'd much rather be able to gear up to be an immovable wall in 3.0).