I think the best way to implement DEC value is to put a floor on rental prices. With the new system, there's no longer an end of season rush that boosts rental prices.
Instead, it's now a wave where prices go up during small spikes in demand and then otherwise go flat. But it's extreme in variation. A card that may rent for 20 DEC/day for 3-4 days in a season can also be rented for 0.1 DEC/day for 10+ days in a season. A lot of the rental mechanisms lead to a race to the bottom of listing at prices slightly lower than the current market rate and this leads to cards - which clearly have people willing to rent at much higher amounts, regularly just getting listed at artificially low prices just because of the way an algo is designed dramatically drops prices whenever there is a slight lull in rentals.
I think if we installed a higher minimum rental price and/or required 3rd part rental services to make the default list price the median price and not the floor, this would help drive up the rental economy dramatically, which in turn would give DEC a real use case that would in turn increase its value.