That change may have been made for cases of divorce, but not for cases where the wife has died. Men can still be sealed to multiple women, but no longer to multiple living women. A couple of years back, one of the Apostles was sealed to a second wife almost exactly one year after his first wife died -- you can be quite sure the sealing to the first wife wasn't cancelled. Women can only be sealed to one man, period.
Polygamy in the afterlife is alive and well in LDS theology. Doesn't bother me, but it seems to reliably make the militant anti-Mormon crowd apoplectic. If only for that reason, I'd really hate to see it done away with :-)
Yes, you are correct. In case of divorce, then both men and women must have their sealings cancelled before marrying again in the temple. Thanks for the correction. :)