Well, developers of lotro have managed it somehow and I doubt they have a bigger team. It should not be that hard, I'd imagine: divide everything by something: instead of doing 100 damage you'll do 10, instead of a mob having 1000 hp he'll have 100. Sure some manual adjustments will be needed of course.
The alternative is what is proposed here: keep buffing some abilities every now and then, or they'll lag behind those that scale better. I'm all for buffs, but let's face it -the change by itself won't really help priests in any form: our heals are capped anyway, noone cares about our dps, but it will make wards of classes with wards a bit stronger, though. I hope more significant changes will follow.