Best you try to sell your card and get the 3070 or up.
I'd caution against this advice. The primary reason being supply considerations. Great, new GPU's are out. It doesn't mean you'll be able to purchase one. In recent years paper releases have become the norm, not the exception. It might be 2 months post release before 3000 series cards are easily obtainable.
Nvidia themselves claim that the RT/Tensor cores have "up to twice the speed", and they used a graph in the presentation, that indicated 1.9x efficiency over the 20-series - none of these things directly equal specific performance gains, though. The new cards will be faster, naturally, but yeah we don't know by how much until the benchmarks are out.
I believe the first part of your post, or the "up to twice the speed" element, was a reference to architectural changes. This does not necessarily mean the resulting performance on the cards will be twice as good relative to the previous generation.
In terms of the 1.9x efficiency, well, as the name implies this is a reference to performance per watt. It's an efficiency metric. Nothing more or less.
At this point I'd completely ignore any of the "it's X times faster" claims. These type of claims lose a lot of their meaning without context. It's true for a very large number of performance metrics (on literally every piece of PC hardware). As with anything the smart play is to wait until independent, reliable benchmarks are available.
I'd add, I'm still curious to see what AMD has up their sleeve.