Every future considerations deal ever ended up with one team giving nothing for the player?
Not all, but most.
At least tangibly speaking.
We may never know what goes on in GM phone calls.
"Remember that futures deal we made last year? Toss in a 7th/retain 10% of this player's salary in this new deal and we'll call it even."
(Like the Vrbata/Fairchild trade below.)
Who knows.
But as it goes, must future considerations turn into nothing tangible or explicit.
Some examples where it did though:
July 17, 2009 - Washington traded Keith Seabrook to Calgary for f.c. - Washington was later rewarded 2012 seventh round pick (#195-Christian Djoos)
December 12, 2005 - Carolina traded Radim Vrbata to Chicago for f.c. - Carolina was later 2007 fourth round pick (#96-Cade Fairchild), which was tacked onto the later trade of Babchuk for Richmond + 4th
June 25th, 2002 - Vancouver traded Ryan Bonni to Toronto for f.c. - Vancouver later rewarded 2003 eighth round pick (#252-Sergei Topol)
February 21, 2001 - Los Angeles traded Rob Blake and Steven Reinprecht to Colorado for Adam Deadmarsh, Aaron Miller, 2001 first round pick (#30-David Steckel) and f.c - Los Angeles was later rewarded Jared Aulin and 2003 first round pick (#26-Brian Boyle)
Various expansion draft agreements - the trade would be described as something like, "Columbus agrees not to select Dominik Hasek", but formally with the league, Buffalo received "future considerations".
There are more trades though were it does not turn into anything...
Adam Cracknell for f.c.
Kevin Poulin for f.c.
Nick Boynton for f.c.
Gus Mortson for f.c.
etc.
And going beyond future considerations, tonnes of trades with conditional picks that never convert, such that one team effectively got nothing:
Josh Green for conditional 4th (not converted)
Carter Ashton and David Broll for conditional 7th (not converted)
2016 3rd for Jimmy Vesey (left as UFA before signing)