The GTX 1070 is still a fantastic GPU.. i normaly skip a gen for example if i was you and had a gtx 1070 i would skip the RTX 2070 and only buy after that.. Unless you need a New GPU there is no point in my opinion.. if your hitting your desired FrameRate and your still happy with the GTX 1070 I would just keep it. Hope That Helps Answer Your Question
Any Question Just Ask i will try and help the best i can