No, the current game mode allows two heroes per side (2v2).
u/ea_charlemagne either misspoke and meant to imply that "Four heroes are playable at once" (2v2), the rule was modified sometime after he made that statement, or it's a bug and they really did mean 4v4.
I believe this was a late balancing change. 2v2 is intended, though we can change it live should we think it wouldn't throw things off.