I think there's some minor tweaks that would be needed for The Order sequel right off the bat. Little things that go a long way. For example, not forcing people to walk constantly, as sometimes this feels restricting. Allow players to run around, which helps with exploration too. Being able to holster and aim your weapon freely when you're playing. Minimising QTEs, or at least, integrating them a little better so there aren't too many varying ones. This is minor stuff that could help a lot in terms of how the player feels.
In terms of the more key design aspects, I feel better level design, and encounter design, would go a long way to help them gaining criticial appreciation. There's a fight right before the end that demonstrates the potential for a more dynamic encounter quite well. More of that with varied enemies in a lengthier campaign would be very memorable. The core gunplay is very good, and they have a solid base in terms of story presentation, so they just need to push themselves further now.
I think there's a lot of potential in a sequel if it's allowed to cook for a little longer. I really liked The Order, even with its flaws, so I'm excited to see them get a chance to really expand on it.