Are you talking about Comfort+, or Delta One? Comfort+ is still complementary on international, but Delta One is not. There are rare op-up's at times due to coach being oversold, but other than that they don't upgrade Medallions to D1 simply because there are open seats.
"Complimentary Upgrades are not permitted to Delta Premium Select or Delta OneŽ flights outside of the U.S. 50."
D1 on international long haul routes was never a free elite upgrade, although DL tends to prioritize OPUPs by status as an unpublished benefit. [I'm not counting the phantom upgrades to WBC during the last days of PMNW, RIP.]