Wasn't able to find any actual study on this so I'll offer my thoughts.
I believe any answer you could get would be kinda relative because model formats and compression have changed a lot over time. Because of that, one 200 poly model in 1996 could be a totally different size than another 200 poly model in that time. Also, you need to take the texture size into consideration. I believe that the texture size over time has grown more than the size of the model itself.
But on top of that, there have been numerous improvements to compression as well. Both, for the models file format and the overall packaging for the models. For my companies work, some of our high poly models, uncompressed, can reach 30 or more meg but once we save it as our preferred compressed format, they drop down to maybe 2-3 meg. You weren't asking for compression but I figured I would still throw it in.
As a test of current model file sizes, I took a 16k poly model (no bones, animation data or texture data) of mine and saved it as various formats that are currently used. However, keep in mind that these formats also save different amounts of information. And for most game companies, they have different standards of what info they want to keep in models so the sizes could be different. This makes it kind of difficult to actually know what the actual models size is without being there for development.
- .fbx = 2.3 Mb
- .dae = 1.7 Mb
- .3ds = 445 kb
- .obj = 856 kb
- .X = 6.2 Mb
As you can see, the same file has drastically different file sizes based on format. I'm not all too sure what standard formats devs were using back in the 90's but I'm fairly sure that they were usually different between companies