This speculation is as sad and pathetic (and justified) as the hand-wringing and whining was that followed the trilogy's conclusion. Rather than post your dreams or predictions about ME4 [sic] why not look at Bioware's track record with the franchise and deal with the reality of what's likely to come in 2015. The best predictor of the future is the past...
(1) I've read that there will be no Sheppard in every article published about this topic. That means that there will for sure be Sheppard, in some capacity, in ME4. Legend or whatever. Ghost or omni-present codex entries. Sheppard's narrative is impossible not to reference if the storyline takes place anywhere in the universe, anytime in the future. No matter what (sweet) option you chose in ME3, pretty sure everyone heard about it...Like we have BC and AD here on earth, the ME universe must have a BS and AS timeline. (Even if they don't call the main protagonist Sheppard, or find find some clever literal way to preclude him, I am sure you can make 'it' look like Sheppard and even make people call your character Sheppard. So whats the difference and why bother...Just admit it. It's Sheppard. And that's fine.)
(2) Not a sequel to ME3? I bet you it is and what's more, I bet you it better be if they (EA, Bioware, PS, XBOX) expect players to not only pony up for the game, but a nex-gen console to play it. I thought all the DLC's were ridiculous as a 'late to the party' player, but spending another $50 on ME3 DLC seems quaint compared to what will be REQUIRED to play ME4.
(3)Sound and fury signifying nothing. The trilogy achieved what it did by offering players, the illusion of a 'choose your own adventure' book set in space on a gaming console/PC. Ultimately, as most of us discovered when we were in elementray school, these stories end in roughly the same way no matter what route you took to get to the last page. It's partly the mechanics of the narrative and partly the fact that it's a story, not reality. As a result, ME4 and its almost certain to follow sequels, ME5 and ME6, are as likley to be a let down as was the conclusion in ME3. This is simply because, you can not make all the possible premutations matter in the end, because that would require all permutations get their own distinct ending. Not happening no matter what the processing power nexgen consoles and PC provide. In the end, it will look pretty, but all will be left wanting in the end...
PS-The opening scene of ME$ (oops, typo) ME4 should be Sheppard in the shower and whom ever your love interest was, being shocked to see him/her, exclaiming, "I've just had the craziest dream..."