So yeah... should we bother with Dailies anymore? Or just throw money at Bioware, and wait to reap the rewards of Pay2Win?
First off, I wouldn't expect to see the new expansion for at least 4 months, probably closer to 6, so, regardless of how the developers implement the gear progression, what you get now will still be useful in that time frame.
Secondly, whether current end game gear is going to be completely overshadowed by the new gear depends heavily upon how the developers choose to implement it. It's entirely possible the item levels on gear (tionese is 51, columi is 56, Rakata is 58) are simply going to increase by 5, such that the 63 gear we're currently using will be more akin to Rakata or Columi was 1 year ago at TOR's initial release. It's also just as likely that the devs will perform a "gear reset" like other MMOs have tended to do and just make Makeb drop grade 63 gear from the introductory quests, but most of that was due to the massive difference between leveling gear and maxed out raid gear in the aforementioned game, which hasn't happened to the same extent here (here, the difference between intro and max is roughly 75% more damage/survivability; in previously mentioned games, the increase was severalfold, in the 3-4 times range).