The RTX 4070 arrives in April, according to some embargo documents from Nvidia that were accessed by Videocardz.
Specifications wise, it seems the RTX 4070 is going to be near the performance of an RTX 3080. Considering this would mark around a 50% increase from the 3070, there's still some generational improvement here.
But, it will likely come down to the pricing for us to see whether this card is worth picking up or not, as for a 3080 performance you wouldn't expect to be paying equal to or even more than an older card.
If the pricing of the other 40 series cards is anything to go by, the RTX 4070 isn't going to be cheap, but by this point we wouldn't expect anything else.