I would so love if they took this oportunity to give a gigantic middle finger to everyone who played Renegade.
'So you think it's funny to alienate every ally you could have had and piss of the entire galaxy? Well now you stand alone against the Reapers and they kill you without a second thought. How do you like that you anti-social *****?'
They won't, but I can't shake the feeling that the Renegade ending may be somewhat of an ass pull or otherwise rather horrific in terms of casualties.
A Paragon can call on:
The Rachni
The united Krogan
The Shadow Broker
The Council
The Alliance
Potentially the geth and the quarians, since your actions in ME2 may have been a sign of a wider reconciliation to come.
A Renagade can call on:
The Shadow Broker
Possibly Cerberus, though according to the pre-released facts not likely
Seems a little unmatched, hmm? A Renagade spends every game alientating all their potential allies, so why in the third game would they rally behind Shepard? What possible reason could they have that is not pulled out of the story writer's arse? A paragon Shepard is a hero, a renagade is a dickhead.