Upgrade games from 360 to One after backwards compatibility is released?

As was already mentioned most of those games already have some type of Xbox One version. The other issue is that Xbox doesn't control if those games become backwards compatible or not, the publisher/developers who hold the liscens do. So they would have
to agree to make the 360 games backwards compatible after releasing upgraded Xbox One versions. Not sure they would want to do that.

Unless they are on the backwards compatible list, they won't work on the Xbox One. But when Xbox Series X gets released it'll have retro compatibility for 360 and xbox one games. They might increase the Xbox backwards compatibility for xbox one too after
release.

The only way you can do xbox 360 to xbox one is backwards compatibles or upgrade offer usually limited to the first year of release of release of the one copy

However there was never an upgrade offer for the ghosts

Yes, that does work with backwards compatible games, but Black Ops 3 is not a backwards compatible game. There are several games that have been released on both the 360 and One and are seen as separate versions of the game. Sometimes the publishers have
deals where you can upgrade to the One version for free if you purchase the 360 version, but it doesn't work backwards.

In order to play Black Ops 3 on the 360, you would need to purchase the 360 version.

Thats what Ps4 does ...Microsoft will do it for free quoted from e3 2015 an a limted amount of games that are 360 only will run on emlator ! Thats why when it was anounced I switched to xbox . DIE DOUBLE CHARGING PAYSTATION DIE !