As I posted earlier (and others have as well), I'm betting Vadic is related to Tasha Yar and had been held against her will by Romulans. Basically, S3 (or the Vadic subplot) will be Nemesis rebooted.
When you're trying to replace Nemesis as a story ending, is it at all smart (from a PR perspective) to re-tread the Nemesis plot premise?
"TNG deserved a better ending... so, here's a slight revision of the same one."