It means that Shocker basically controls the world, with their soldiers marching on the streets and such, and obviously they still have their usual armies of monsters and such. They always intended to control the world, so I don't get why you think this is odd.
It's repetitive, since it seems to be retreading Let's Go Kamen Riders, which had a similar concept (alternate timeline where Shocker conquered the world), but this one seems to have a "Shocker vs Rebels" take and initially the protagonists are with Shocker, so it might end up a fairly different experience.
I think it's odd because I know they won't really show the effects of Shocker taking over the world save for shots of the army marching pass world landmarks like the Eiffel Tower for example.
The movie will probably only show the conflict in Japan, which is what the focus on Shocker was mostly at.
So from that point of view, not only is it repetitive, it's also pretty pointless to make it a main plot point in the movie.
Because again, it's just Shocker running amok in Japan but now with some window dressing to make it look like they are a big deal by taking over the world, which they will probably not show in great focus or detail.
It'd have more impact if they showed other Riders fighting Shocker troops in other parts of the world instead of solely in Japan.
And I get the budget and filming restraints prevent them from doing that, and Toei should have know too, so it just makes this whole Shocker plot all the more pointless and shoved down our throats.
A previous trailer showed V3 seemingly saying something to Rider 3 while they fought. There's also an older picture with Rider 1 talking with him (in a place different from the one where he's defeated). I guess Rider 3's equivalents of those scenes will be mostly with suit-only Riders.
The problem with that is Sango's development is only through in suit, replacement VA only Riders while Drive gets actual characters and returning Riders to help him.
The focus is completely backwards, especially given how much promotion Sango is getting and the fact that he really needs that development as a character.
And I get it, Drive is the current Rider so it makes sense he gets more focus.
At the same time though, his movie character arc is utterly pointless given how he's already an established Rider and a cop for crying out loud!
For Sango, he probably couldn't carry a solo movie, which makes sense, and the problem is that the only characters he could connect to will probably never come back to reprise their roles.
To me, they brought up Sango too late.
They should have done this movie during Gaim's run since the show always blurred the lines of what a Rider was.
So it'd make more sense for Kouta to team with Sango instead.
Plus they somehow got back Ichigo's actor for HvS, so instead of HvS, they could have just made this movie instead.
But they'd still probably ruin the movie since I bet they would have stuck with the whole altered timeline plot point.