We have similar rigs and uses and I just went through the same situation. Mine is a 6700K @ 4.5Ghz and I just got a 2080 Super Hydro Copper and added it to my loop (was GTX 1080) with a 2560x1080 144Hz monitor.
I waited on Zen 3 but didn't enough of a performance jump to justify a new mobo + CPU so I went with a custom D5 / HWLabs loop so I can hopefully wait a bit longer.
Overall my CPU can still handle most games quite well, there are a few CPU intensive games that do cause me to bottleneck a bit such as The Division 2 and Far Cry 5. GTA V and Assassin's Creed also seem to show some bottlenecks for others with a 6700K.
Overall I'm still happy with my performance and an waiting until 2021/2022 if I can to see AMD and Intel's new chips and hopefully DDR5 if we're lucky. I wouldn't bother upgrading unless you're going to a 9900K or 3900X.
I play 1080p with mid settings cause if I try high or ultra the games starts lagging and recently my temps shoot up after few hours of playing
Seems off. I play 2560x1440 now on my i7-4790k/GTX 980 and still mostly Ultra and High settings depending on what games, but admittedly I don't really play modern AAA titles. Since you're at 1080 and a Ti, seems you should be doing better than me in that regard.
Really the only game I could see possibly forcing me to upgrade is Cyberpunk 2077 when it comes out. But I'll wait and see.