It doesn't really need to be implemented because you would just need to change to the old Elo system to achieve the wanted effect.
Whole History Rating is already based on Elo, but you can see it as a timetravelling rating system, so your rating now is not fixed and can change as soon as any future game is played by potentially any players.
However, if the game is played far in the future, it will change your rating less or if the players involved in the future games are not well connected to your games(imagine dividing the world into timezones where US player never play EU players for example) it will also change your rating less.
I like time travel. :D