I think in some very specific cases, this might be true. The 3060 has a smaller bus with GDDR6 at the same (presumed) speeds. It has more memory, sure.... but will that narrow bus bottleneck the core? Only benchmarks will tell.
I have a 2070 ITX right now; I would have to mod my case with a Flex PSU for anything larger. At present, I don't feel that anything is worth the hassle. If the 3070 had more RAM, or maybe faster RAM, then that would be a different story..... I just feel that the 3070 will age too quickly.
So a while back I accidentally got the 3070 instead of the 3080 while doing the rapid split second combo buying. I decided to roll with it anyway. I'm running an Ultrawide 3440x1440 monitor, and a 4K TV OLED TV off the card. It's not a bad experience, but you are right. It will age quickly. Right now, I plan to trade up to a 3080ti whenever it actually launches. I'll also be posting some Ultrawide benchmarks soon on it.
Slight tangent... For the new people here, let me show you the SFF rabbit hole that you can get yourself into....
In the meantime, I just picked up a Ghost S1 due to the lack of 70 and 80 class ITX parts. Ampere GPUs are just...big. I'll repurpose my MI-6 as it's still my favorite case of all time. 3060 12GB will probably make a pretty good video editing card, which is actually what I originally built the system to do.
Ampere has been a bit of a pain to me. I had gone from a 980ti blower to a 2080 FE. I hadn't planned on 300mm lengths becoming the norm. The 2080FE cooked my 8086K in the NCASE M1...so I got a Cerberus ATX. That did ok until the PSU burned out from heat soak. I upgraded to a 9900K and full ATX board, and moved the 8086K back to the NCASE but now with no overclock and with a blower 5700XT. Then I realized that the Cerberus basically limited me to the 3080 FE..which is impossible to buy. So I went to a full ATX case...albeit a small one by modern standards. It's the Silverstone Seta. It's a nice case, albeit quiet large. However, even with this case I'm limited to 295mm cards if I use a front mount 280mm AIO.
I was going to put the 3070 in my wifes machine until I realized the 2080 FE barely fit in the her NZXT H210 with front mount AIO. So I figured I would use it for my HTPC....which is currently in the MI-6....which was supposed to get a 3060ti or better this gen! Full circle....