For me, the development of the next episode is likely to be faster.
For at least 2/3 reasons:
1- the battle system is ready.
Just apply it to the next characters, and it's done.
2- the biggest city of the game, Midgard, has already been built.
The remaining towns of the game, including the Gold Saugers, is considerably smaller than all of Midgard.
Which will make the construction work of the probable openworld much easier to manage.
For the rest, there will be a truly very convincing, and realistic, open world that includes the possibility of being able to visit many places, many cities and many dungeons.
If they can do this already from the second part, then most of the Remake work will already be done.
(since it will be enough to apply this work also to the following parts)
[probably always using the Unreal Engine 4]