Riot Games offered a glimpse into the future of Teamfight Tactics, briefly mentioning the new design philosophy that will make sure balance changes to the game aren't as sweeping.
There is a lot to look forward to in Teamfight Tactics Set 6 but perhaps the most important change will be in Riot's approach to balancing the game. Namely, it was pretty hard to keep up with TFT as it is, with the sets changing the ecosystem drastically on a pretty tight schedule but what made it even more difficult were the balance changes to the current set that would have an almost identical effect.
Riot calls this phenomenon "Balance Thrashing" and it specifically refers to changing the specifics of certain team compositions so much that their value changes exponentially. For example, a nerf could send one of the best comps in the set flying from S-tier all the way down to the garbage zone of F-tier where it would never see the light of day again.
With Set 6, the team will apparently strive to balance the game more carefully, without introducing such sweeping changes. The balance might take more iterations and more time this way but the lighter touch will probably allow the team to aim much better and deliver more variety in team comps as a result.
There are a few more highlights from the dev insights , such as Hextech Augments, which are replacing the Shadow item mechanic but they won't be tied with a negative effect as the devs are striving to decrease mechanics complexity.
Another highlight includes the removal of ranked rating decay so you won't be under so much pressure to keep playing, even after you attained the rank you might be satisfied with.