Rogue doesn't need a fix. Pathfinder just needs to be balanced more towards the claims of the base system. Against CR appropriate enemies and challenges, Rogues perform completely viably. They simply don't min/max as hard as other classes.
If the game were more consistent in the way it's optimization is executed, you wouldn't hear complaints about rogues. That's party of why I'm excited for Starfinder. I'm willing to bet the system will, while being backwards compatible, be more consistent throughout.
The original rogue was fine with with appropriate CR enemies and challenges up to about level 12. That's when they got really bad, not instantly at level 12 but level 12 was the downward slide. The issue was the rogue couldn't hit well enough to deal with increased danger they put themselves in to get sneak attack due to stalled defenses. So it was hit with 25% to 50% of your attacks and get squished in 1 round of full attacks. So the rogue then hangs back avoid the killing blows but not getting their sneak attack in. This was typical of the old rogue. Unchained fixed that with Debilitating Injury. Now the unchained rogue only needs to hit once which they normally do and they get +6 at 10th or +8 at 16th to hit. Now the iterative attacks hit more often. On top of that they can apply two injuries and reduce the attack bonus of the enemy by the same amount. The rogue offense and defense just jumped significantly.