I think SW: TOR will do really well, Bioware don't often make bad games (Dragon Age 2 doing surprisingly badly, but given that EA now own Bioware to an extent, it wasn't too surprising ), and I was going to join it, but after playing FFXIV I don't have the desire to play TOR anymore.

That being said I doubt FFXIV will suffer too much from TORs release.

And as for TORs content, I'm pretty sure Bioware made enough money from most of their games being huge successes and making game of the year on multiple occassions for them to afford to keep using the same voice actors for extra content. (e.g/ Mass Effect 1 and 2 used all the same voice actors despite the huge gap in years between their releases)