The idea would be to use Assimp to allow the engine to import models from those that the library accept, then using Assimp convert or export the models to .obj or .dae, then the engine converts that model to .model or .animation so it can be used, by doing this we are reducing how much of the current engine we have to change, we only have to create or reuse a plugin to convert from .obj to .model internally on the modeleditor. Currently the engine has a .dae to .model converter that with little to none effort can be used, so the will be almost none compared to what we would have to do if we want to support those models format directly, I believe that this approach I propose is the fastest and easiest.
The idea would be to use Assimp to allow the engine to import models from those that the library accept, then using Assimp convert or export the models to .obj or .dae, then the engine converts that model to .model or .animation so it can be used, by doing this we are reducing how much of the current engine we have to change, we only have to create or reuse a plugin to convert from .obj to .model internally on the modeleditor. Currently the engine has a .dae to .model converter that with little to none effort can be used, so the will be almost none compared to what we would have to do if we want to support those models format directly, I believe that this approach I propose is the fastest and easiest.