So I've got some info on the Destiny Expansions.

[Euphoria14]

Raziel123 said:

Grounded? Difficulty mode for SP -> entirely optional. Would not be optional if it were for online content.

Can still play Destiny, without the expansions -> optional.

You know, just like Reaper of Souls for Diablo 3!!! Believe it or not, you can still play Diablo 3 without the expansion.