Maybe some of you remember the Trials of Atlantis (ToA) Expansion in DAoC. Before release it was claimed, it would not have any influence on the Realm vs Realm combat. Actually, it changed the PvP a lot due to more powerful abilities and items that were available. Players that were only interested in PvP were "forced" to do extensive raiding to get Master Levels and Artifacts to stay competitive... many players left soon after release of this expansion.
Personally, I dont mind PvE expansions and character advancement after hitting max level, but it should not influence PvP too much. Many players just dont have the time to do extensive raiding every few month to stay competitive in PvP... some may just not be interested in PvE raiding at all.
What do you think?