Definitely not Basic Economy.
This page says:
Beginning January 1, 2024, Million Miler Status will be earned via flight miles flown (excluding Basic Economy fares) and added to your total Million Miler balance. Any MQMs already earned toward Million Miler Status will remain.
No mention of it being Delta metal only, though I'd really like to know that answer, too, since that's going to have a lot of bearing next year for me when choosing between DL and VS on JFK-LHR.