Jean is alive, isn't the Phoenix, and isn't part of a love triangle right now in the comics and it's wonderful.
Jean is Xavier's first student and the most senior X-woman. She's hugely passionate and empathetic, combined with a great amount of power and a righteous fury. Jean brings teams together and keeps them together because everyone cares about her and she cares about them.
She is consistently a spokesperson for mutant rights. In Morrison's run, Jean ran the press conference that initiated relations between humans and the mutant school, fiercely defended the students, and organized the international X-Corps. Today, she's a visionary bringing her plans to the U.N. Jean, more than anyone, has trained and prepared for a type of visionary diplomatic leadership, able to best articulate why the X-men exist.
You don't need the Phoenix, Cyclops, or Wolverine to have Jean shine. She's a character with an infinite amount of potential in terms of what she can achieve with her life, but has a power inside that can help or ruin everything (sometimes this power is the Phoenix but it can also be her telepathic/telekinetic surges). Losing Jean should shake the X-men to their core, but she does not have to die (and I especially don't see Marvel shaking the X-men's core for a long time, thankfully).
The Phoenix is a visually exciting and iconic way of highlighting aspects of Jean's character but it is not essential for her character development.
As a model X-figure, Jean can foil with other characters. Kitty's inexperience contrasts with Jean's seniority. Emma's sense of telepathic morality and propriety contrasts with Jean's ethics. Cyclops' impersonal leadership style contrasts with the emotional bonds Jean forms. Iceman's sense of humor contrasts with how seriously Jean takes the X-men. She's a foundational pillar.