And he has the best line in the whole trailer.
But yeah, this probably would have been a much better idea to revisit once (if?) the X-Men are fully integrated into the MCU. Then you could have the cosmic aspect and it would give a better sense of the power of the Phoenix Force. I'd be willing to bet Disney/Fox/Marvel (sheesh) is probably going to reboot everything X-Men after Dark Phoenix, though. Unless they write something weird into Avengers 4 ("Hey look, not only is everyone alive again but now we've got all these mutants!") the X-Men don't fit in the MCU's timeline.