My gut feeling is that you'd be hard-pressed to come up with a concrete example of two bonus actions that could not be handled just as effectively by using one normal action and one bonus action.Rather, I wonder if there will be a FAQ about converting a bonus action into a normal action. It's probably a corner case, but for example a Cleric casting Healing Word (a bonus action), can she cast it also as a normal action? If she's not actually using her normal action this turn, then it's irrelevant. But what if she has another ability X that grants a bonus action? By the rules, she can't take 2 bonus actions in the same turn, and the intent of such rule is to prevent too many action in a round (max 2). What if she is not taking her normal action, but wishes to cast Healing Word and use X? That would mean technically 2 bonus actions but 0 normal actions. By the RAW, it's not possible, however by the intent this may be acceptable, since it's still 2 actions (and stuff you can do with bonus actions is so far typically less or equal to the stuff you can do with your main action). This is what I mean by converting a bonus action into a normal action.
Most bonus actions are things that can already be done as normal actions. Those that are not (such as spellcasting) are restricted for other reasons.