Also for it to be done properly. It would have to be an expansion. If they are going to give us DM mode and a toolset to build upon. It would have to incorporate all the levels. If it is split up into two different games it would not work especially if they updated their engine to 5.0 for part 2.
If they do not do expansions as it has been suggested. To make this a complete game they would have to give us a 20 level cap game, DM mode and a toolset. Otherwise, it is just a demo game that becomes abandonware. (why do I feel like the fence is getting barbed wire and I will have to jump off).