Two things to note if this same PNR for companion upgrade goes into effect:

(1) on one side I would welcome it, because I always split family member reservations after booking to ensure I get the Diamond upgrade but then figure if they are not Medallion that they will have to pay the luggage fee because they are no longer on the same PNR. --(well maybe not now that DL AMEX card holders dont have to pay);

(2) On the flip side, this same PNR policy would often be a revenue gainer for DL because if my companion wont be upgraded with anything less than a K fare, then I am forced to buy at least a K fare also because travelers on the same PNR must have same class of service. I also see the reverse problem sometimes as when I will fly next week to Hawaii: I would have possibly bought myself an M fare to net the 50% Medallion qualification bonus but then my companion travelers would have also needed M fares since we need the same PNR to use the systemwide upgrades. Thus, in this case, I bought a lower priced ticket for myself than I otherwise would have because my traveling companions don't need the extra MQM and I would not want to pay extra for them, so we're all traveling on a K fare instead of one M fare and 2 K's.