Do we ever find out who and what the future considerations are? Like does the GM just call up the other GM and is like “I’m calling in a favor. I’m gonna need that 7th round pick.”
Not really, no. "Future Considerations" is really the legal definition of "nothing", since you can't trade a player for nothing.
But sometimes it might be a consideration in a future trade, maybe swapping seventh rounders, or something tangible like a dollar or a washing machine.
Think the Hawks were kind trading Subban as he might get NHL time with the goalie depleted Sabres.
We see a couple of these type of trades every year, one team helping another with minor league swaps.