TOS wasn't a serial. Each episode stood alone. Spock had the most developed backstory, Kirk kind of had one, but the other characters had no backstories at all. We knew hardly anything about McCoy, Scotty, or the rest. Yet everything was fine.
The TOS movies had a sort of trilogy in TWOK, TSFS, and TVH but it wasn't a forced trilogy (as in one movie foreshadowed the next, or seeing all of them is required to make sense of things).
Given what precious little we're going to see of these characters right now (one more movie and that may be it), I'd really like to see the third movie be a totally independent story with fully bloomed characters comfortable in their duties and already earning a reputation as a special crew doing special things.
That said, by title alone, "Into Darkness" portends an ending that may require the loose ends to be tied up in the next movie.
In any case, I'll take what comes and hope to enjoy it.