I agree totaly with Chems, if you do DLC on items, this will end up in an frustrating point, even if it is only in terms of "theming", where, if you dont have bought that theme, the item changes to a generic theme.
This will smash down the whole game and takes away its wonderful magic.
Its easy to do, and there is also an intelligent way.
They SHOULD do paid DLC (at a fair price), for keep up work on the game, without making money the project will die. I also see no sin in doing an PC2, why not constantly updating this game, so its fine for years instead of only a few 24 months-periode?
DLCs should be done in a way no one gets "hurt". If you download something and it doesnt appear (missing DLC-Part) or it changes its visible style (missing DLC-Theme) its bad.
They sould do it the following way:
Open MOD on a supported way, so people can do their own stuff and import them. With that you get a near unlimited way of importing stuff. Customer have lots of possibilities then and it gets not boring waiting for new content, because everyone cancreate and import it.
It shouldnt be that compliacted to create an import-editor, so people can use this to import stuff correctly to the game, of course work, but not that much, as long it start with static parts only.
DLC should only be done in non-harming ways, that means:
Make DLC for example water : better water-simulation, waterfalls, additional water-rides, terrain-tools, ...
PC is for creative people, so why not making advanced editors as DLC ?
A better coster-editor with advanced features. An editor for animatronics, an editor for Dark-rides, ...
That way everybody can download every stuff without restrictions, but if you want to create the stuff by your own, you have to buy the editor aka DLC ...
The base game is cheap, you can try it, if you like it and get inspired by it and you want do more by yourself, you can buy DLC to extend the possible options. This is a fair way to make money with DLC (fair price).
Ideal for kids also, base-game is cheap, for adults who wants to do more: they have to pay mor to get it ...