So Cerberus now controls the Citadel and is working on their own Crucible. We know that the Reapers are going to attack the Citadel themselves pretty soon and Cerberus is not going to be able to resist that which means the Crucible (if Cerberus even manages to build it) will never be used.
Without the prospect of the Crucible in the first place then there is no reason for a joint assault on earth (since that was as much to reach the Citadel as it was to liberate earth). Despite Liara's and VS's best efforts there is no alliance between humans and Asari. Thessia falls.
The quarians get wiped out. The geth become reaper slaves. Tali dies never having set foot on Rannoch.
Aria dies on Omega. Jack dies at Grissom Academy. Jacob dies wherever it is he dies. Miranda is killed by her father. Legion is a slave. Samara kills herself. Thane dies. Zaeed probably gets killed by Cerberus on the Citadel. Javik is still buried (I can't remember how we even learn about Eden Prime, maybe VS is sent and Javik is rescued).
That leaves Kasumi, Wrex, Garrus, Liara, VS, Joker, EDI and James.
Most of those die when humanity makes one last ditch effort to retake earth and fail.
Tuchanka falls.
And just because it is a pet peeve of mine so do the Raloi and Yahg.
The cycle continues.