Many in the railfreight industry seem convinced that the downturn in freight volumes is only temporary, and the upward trend we saw before the recession will begin again in a couple of years. So it's quite possible the plan to overhaul a few 60s, as DBS suggested before the recession kicked in, could still happen.
Most of the growth over the next decade is expected to come from intermodal traffic, which is more suited to 66s than 60s (unless we get round to running longer, heavier trains). Perhaps with greater demand on the 66 fleet there might be a good case for spending some cash on a few 60s. I think DBS understands the economic situation will improve and they will probably need their tugs again at some point in the future...