Arena became so boring that if it wasn't for material to Squad Arena Store where I'm still missing few characters, I would stop bothering about Arena completely.
The problem with arena is power creep and zero variety. Top 50 is almost entirely Revan only but even on lower ranks, there is almost no variety either. People are still fighting the same boring teams and unless they have one of the team suitable for their rank, they just don't have a chance to compete. Building a new team takes months even if you are not F2P player - unless you are ready to spent fortune.
On my rank it is mostly Bastila lead followed by Night sisters. There are few players who are trying to succeed with Palpatine lead, Imerial troopers, Bounty hunters or First order but their investment into their teams must be significantly higher (gear and mods) to stand a chance against average Bastila teams.
It looks to me that if you want to play Arena and have at least sign of fun you need either Jedi (Bastila or Revan lead), Night sisters or Traya. All other teams have minimal usage and are not competitive.
This can't go forever. Answer to strong teams and characters can't be releasing a new stronger character or reworking existing one to make it significantly stronger (like it was done with Zombie).
Arena needs different approach to be fun even for players who don't have one of current super teams and I believe Territory Wars show the way how to make it more attractive by bringing in bonuses. Let's say that we would have 4 days per week Vanilla Arena and 3 days per week Arena with bonuses or penalties to different teams which would rebalance power.
Going this way allows limiting power creep and making characters which are not Arena viable interesting again. Players who invest to strong characters will still be able to use them at full power for several days per week and there will be few days where people will need to experiment and really compete.