I have a feeling that Paradis team might be planning to conduct a preemptive strike to eliminate Reiner, Zeke, and other Marley's shifters.
In chapter 93 we can see a suspicious figure that resemble Eren spying on Reiner
Also, assassinating/kidnapping Marley's shifters is actually a pretty clever idea
- There is no reason why Paradis should just wait until Marley attack them. If they allow Marley to prepare for the invasion they have to fight not only five enemy shifters but also Marley conventional army equipped with modern rifle, machine gun, cannon, and also titan bombardment from zeppelin.
- Marley military power is heavily depended on their Shifters, if they lost all of them the other nations that hate them will take care of them and Paradis might not even need to fight further war.
- Reiner and the other shifters are currently heading to their "hometown", Liberio Internment Zone to rest and recuperate with their families so they will not be surrounded by heavily armed soldiers and cannons, this is a very good opportunity to kill/capture them.
So it might goes down like this:
Reiner and other shifters arrive at their hometown and reunites with their families, we might see reiner and bertholdt's parents and Annie's father. They throw a welcoming party to celebrate the war's end, but while they're celebrating some suspicious shadows are lurking on roofs and backstreets.
It was then revealed those shadows are the new survey corps units consisting of veteran members (Eren, Armin, Mikasa, Levi, etc), and new elite recruits armed with the latest 3DMG, thunder spears, and other anti titan weapons and trained specifically to fight titan shifter.
This plan will probably failed since it will be too anticlimactic if the war end this easily, but Liberio might turn into a warzone and some characters might be killed. Colt has a good chance to be killed off in this battle since he didn't have further purpose in the story and it will be a good chance to give character development for Falco.
It also a good setting for Reiner and Eren last fight and set up for Falco to inherit the armoured titan.
I admit this is just pure speculation and I might miss entirely but I just think it will be interesting if the story goes this way.