An announcement has been made that alongside the Command & Conquer Remastered Collection release on June 5, 2020, the source for for TiberianDawn.dll and RedAlert.dll will be released under the GPL version 3.0 license. The full announcement has been made by EA Producer Jim Vesella on /r/commandandconquer.
EA will also be releasing a new Map Editor, which will allow users to design and create maps, units, replace art, etc. and have even created a new custom unit the 'Nuke Tank' screenshotted above. Furthermore, Steam Workshop will be added for sharing maps and mods.
Full announcement: