It’s hard to make predictions, especially about the future.
I would expect that, not only do we have a GeForce 4000 series in 2023, its equivalent cards to today’s 3000 series will sell for fewer real dollars then than the 3000 series does now. This is because development is ongoing, AND because the world factors contributing to the “chip crunch” are being solved with multiple companies building more chip fabs, some of which open 2022/2023. (They’ve of course been under construction for a long time!)
That being said – developing on a 2060 means that you won’t accidentally build a game that won’t run on cards below a 3090. Even a 2060 is pretty fast, compared to intel integrated graphics, so you don’t necessarily have to upgrade.
If you don’t already have a very fast M.2 SSD in your computer, then that’s probably a much more worthwhile upgrade, for example.