User blog comment:ExSturminator01/Mass Effect 3 Predictions based on ME2 hints/@comment-1881161-20100211050906

Bioware will most probably base ME3 on dragon age origin where shepard will need to gather allies in the war against the reaper so instead of recruiting squad members for his crew he will recruit allies like the Geth, Rachni, Batarians, Krogan and show the council what they can't do for the last 1000 years unite the galaxy because all the race that shepard gather are hostile to the council race in the past.

Ash/Kaiden will make a return to what role is still unsure. Whether shepard destroy the collector base at the end of ME2 will probably be a big influence in ME3 and the information you got from the dead ceberus operative did you upload to the alliance or cerberus or kept it for youself for EDI to decrypt.

The Nomandy SR2 will probably be the flagship and get to have more upgrades to it, EDI will will have more upgrades added to her as well faster processor and memory upgrades the crew might be the same if shepard was in time to rescue them from the collectors and the all squad members will return if shepard did not sacrifice them on the sucide mission.

As to where the final battle will take place one can only speculate but i think either the citadel or on earth as the reapers really hate humans that they even when as far as building a human form reaper and harvest humans to power it.