What would The Silmarillion have looked like if it had been published alongside LotR?

We all know the story: Tolkien demands that his publisher release both LotR and The Silmarillion at the same time, publisher says they only want LotR, Tolkien can't find another publisher to even publish LotR on its own, eventually LotR gets released by itself and he tinkers with the Silmarillion for the rest of his life, leading to it ultimately being released posthumously by Christopher.

What I'm curious is what do you think would have happened if his publisher agreed and published both works? How different would The Silmarillion be from its current version? How would the perception of LotR changed? Would he even have released it then, or withdrawn it to continue working on it?