As SE_JonF said, there is no poly limit to a file. I have files with close to a million polys in them. The poly limit only applies to exports. Except when you’re exporting to Unity or UE4. There’s no limit when you export to those engines. I’ve exported a single 400k poly object to Unity as an FBX file and it works fine.
Also, for the 2016 version that just came out, the poly count limit for other exports has been raised to 100,000.