"We also received a lot of suggestions on how to improve Seasonal mods. Starting next Season, the Seasonal armor mod socket (e.g. Undying Mods, Dawn Mods) will also be able to use mods released during the Seasons before and after the armor piece was released.
For example, armor with a mod socket from Season of Dawn can now equip Dawn Mods, Undying Mods from Season of the Undying, and [Redacted] Mods (from Season of [Redacted])"
That is what bungie said in the Valentine's Update. The part that specifically catches my eye is "will also be able to use mods released during the Seasons Before and After the armor piece was released." Mods released before such as obelisk mods??? Because that's how that reads. If the answer is no then bungie should clarify.