Somebody called?
At VSTEP the main modeling tool is 3DS max, which is also from Autodesk. But file formats ain't the problem here.
Practically any 3D modeling tool has a .3ds .obj or .fbx exporter if not more.
The main issue is if VSTEP has the need to add the new content.
What most people think (and I don't blame them) is when a model is done, it's simply sent to VSTEP and they'll add it. But implementing vessels involves a lot more than just the modeling stage.
Firstly, VSTEP needs permission from the original owner to be allowed to release any vessel if it's non-fictional.
In this case, Celebrity cruises should approve this model.
Then there comes the converting. Dynamics need to be made, walktrough paths need to be laid, functions need to be programmed, and when that's all done, the DLC needs to be prepared and approved by Paradox to release.
This involves much manpower. So VSTEP must have real intentions with the model in order to invest the time and money into it. If someone for example creates a tugboat for SSE, it's not guaranteed if VSTEP is planning to release a tug DLC for SSE.
It doesn't mean it ain't possible to get your vessel inside SSE. Just make sure in advance that there are no legal issues with copyright and that VSTEP has interest in creating the specific DLC.
What is VSTEP planning right now?
Well, firstly they need to get the patch and Inland DLC released. So I cannot say anything yet about future plans. I already did share some ideas with them though.