RE: Pokemon Omega Ruby - Alpha Sapphire will get the same aesthetics as gen 2 remakes?
It is really impossible to say right now what extra content they're going to include plot and story wise, especially because that's not the kind of thing that's easy to advertise or even should be advertised. We could get an expanded plot, the other two remakes did, but we're not likely to see any evidence of it in trailers; they'd behave too much like plot spoilers. Easier to advertise features like contests, because if doesn't give anything away, but they can't be like "play through Wallace becoming champion and watch Juan take over the gym" because it gives a lot of plot away. We all know or can find out the original plot of the games, but they wouldn't want to give away everything they added. I don't believe the other two remakes ever mentioned the extra story content they did. Their could be no new plot content besides primal reversion, but we're not likely to know until release, because they won't show it if its not there, and they probably won't show it if it is.
As for pokemon following you, its a feature I miss too
. However, its not likely we will see this return in any game any time soon because it would take so much extra work. We have over seven hundred Pokemon, some even have different forms which add even more. They'd have to do individual art work for each Pokemon AND code that all in the game, plus we dont just move in a simple four directions now, which doubles the artwork needed in HGSS. It would take a lot of memory to do that, I believe it's the same reason only pikachu speaks in the games, because to give it go all Pokemon would put to many strains on the system and it would lag.
As for new areas, who knows? Again, its something we are most likely to see after release. I think their is a chance they will give us a new mini region to explore again like Sevii islands, but that can't be confirmed or denied either way.
Secret bases and contests aren't concepts new to the series, but they've been updated and improved and added newly to generation 6 as features. We could be getting some other new feature they haven't shown yet, such as the battle frontier, but we don't know yet. I personally think the frontier will make an appearance again.