I think they'd be pretty safe with something a bit slower than the 4070 Ti for 1440p/60. Looking back at the 2060 review, it was between 60 and 75 fps on the more demanding games at the time at 1440p/max:
NVIDIA's GeForce RTX 2060 doesn't seem cheap at $349, but this new card has enough steam to beat AMD's RX Vega lineup at better pricing and with much better power/heat/noise. Actually, the RTX 2060 obsoletes much of NVIDIA's GeForce 10 Pascal stack, too.
www.techpowerup.com
In this light, it makes sense that you're struggling a couple years later if you don't want to turn settings down too much. If we make a similar comparison with the 4070 Ti, we can see that it's typically holding 100-120 fps in today's most demanding titles:
The PNY GeForce RTX 4070 Ti OC comes with a fantastic cooler paired with outstanding fan settings that make this card whisper-quiet, even under full load. What's even more impressive is that PNY can achieve this with a close-to-reference design PCB at a very reasonable $830.
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Of course, how cut down the 4070 will end up being is unknown, but assuming it's ~20% slower, they would still have a pretty comfortable buffer - at least, more of one than the 2060 had when it was new.
P.S. - I'm on the very similarly performing 1070 Ti shooting for 1440p/120Hz, and although a lot of the games I play are older and I'm okay with lowering some settings, I too am starting to get the upgrade itch