Haven't we just had this discussion?
I'd like to see the Midwestern BOS and the airship/vertibird and the power armour/super mutant pair patrolling suggests to me that they maybe in Fallout 4.....its also possible that Lyons' BOS could be pushing north and the Outcasts might have moved north looking for a new source of tech.
I don't want to see either NCR or the Legion on the east coast simply because its so unlikely, the NCR is over stretched trying to hold on to the Mojave, they have no real reason to travel 3,000 miles though god knows what hazards. The Legion also has no real ability or need to be pushing their troops all the way to the east coast. It would take decades (maybe even longer) for the Legion to follow its usual pattern of expansion all the way to the east coast.....if Caesar is dead it is even more unlikely that they will be during that much expanding of their territory.
The only NV faction I could see making the trip would Yes man and his robot army, they could probably roll straight over anything on route and travel day and night with no need to scavenge/hunt for food and water.
Does the eyebot signal the presence of the Enclave or is it just pre war tech the Institute is using?
Super Mutants appear to be in the game, maybe both West Coast (with the Midwestern BOS) and East Coast varieties.