Only just finished my first watchthrough recently, but I have a pretty clear idea in my head of where everyone would be 11 years later.
Hannah: Quit or got fired from her teaching job within a year of starting. Continued to balance jobs until she rushed into marriage with her next boyfriend because shes drowning. Got divorced. Now dating someone else (probably a guy, but it's not impossible Lena's ideas about her sexuality are wrong) and back to teaching at Grover's school. Surprisingly at peace.
Marnie: Has managed to get a pretty decent life together. New okay husband, okay job, maybe a kid or two. Absolutely miserable.
Shosh: Built exactly the life she always wanted and absolutely loved it for years. Extremely successful, amazing husband, wonderful friends. Puts on a bright smile every day now to hide how utterly bored and unsatisfying it is to have no more ladders left to climb and no more goals to check off.
Jessa: There needs to be an inciting incident to get everyone back together, and Jessa is the perfect hurricane to make that happen. After a decade of continuing to drift through life, she had a baby, she doesnt know who the father is, and since Adam died in some theater accident, the only person she thinks she can try to get to help her with it is Shosh, who proceeds to try and get rid of her by trying to get Hannah and Marnie to help her. Has not changed a bit.