The Green New Phyrexian Praetor Vorinclex, Voice of Hunger is quite the beast, his second ability reads:
If an opponent taps a land for mana, it does not untap during his next untap step.
Say my opponent taps his land for mana, and sometime during his current turn or my next turn, Vorinclex dies somehow. Do his lands remain tapped for the extra turn as originally stated, since they were tapped during the time Vorinclex still lived, or does the effect end immrdiately upon his death, allowing my opponent to untap them as usual?