What has been made by QQ can be unmade by QQ!!!
BioWare did leave the door open for more same-faction games like HuttBall.
The reason why cross-realm stuff makes the community worse is because you are no longer accountable for your actions. In a small community reputation means something and those coming out of WoW and into SWTOR, which will have small communities, will learn quickly how fast the the server will alienate you.
It is not hard to blacklist someone on the realm forums or in chat calling them out as a Ninja or being AFK in instances. I'm sure everyone has seen this type of thing before when they played Vanilla. In fact on our server we had one guild that was compromised of all the blacklisted people because they couldn't find any place to go, that guild got extra sauce from the opposing faction and no one in the know would ever group with them.
Cross-realm stuff doesn't allow for the community to respond in a way that has repercussion for the offender so it IS the reason WoW communities went down the toilet.
And honestly, it wont matter in TOR. They don't have level brackets in pvp. everyone between 10-50 fights together (lower levels get bolstered up to level 50 stats).