The Comet 3s would still be trucking along if it wasnt for compatibility issues with other cars with braking, lack of automated destination sign system etc. The cars still have life left to live and could be overhauled and carry on. The premature retirement of the cars was a sin on NJTs part as solid sets of them would continue to serve fine for AC, BH shuttle or dedicated Meadowlands shuttles. You dont need anything too technical for that to work. All of those early bombardier cars based off the pullman designs have been fairly successful. The Superliner cars made by bombardier also are working without much issue.
No good deed goes unpunished.