Mass Effect: Legendary Edition was confirmed by EA last year as a remastering of the original trilogy of games, as an attempt to "modernize" the experience, and we might now know the release date, thanks to a new leak from retailers in Singapore and Indonesia.
Two retailers, Shopitree and GSShop, leaked the date of March 12th in error, which would be consistent with EA's previously claimed 'Spring 2021' release window. The date has not been officially confirmed by EA, however, with all other retailers showing placeholder dates.
That being said, the fact two separate retailers have arrived at the same date is telling, but could, of course, be subject to change.
The remake of the original Mass Effect is not a from-scratch rebuild, but will be a "modernized" experience, allowing players to experience the original in the "best possible form" - so I imagine, as with BioShock, there'll be some updates, compatibility fixes, and generally enhanced textures and graphical effects, all baked onto the original engine.
It'll include all the content from the first 3 Mass Effect games, plus the DLC, and is arriving in the Spring of next year.