I wouldnt upgrade just yet, at least not on intel.
To being with 4790k is a very capable chip and can still run everything to date, especially if overclocked. Now speaking intel they just recently announced 10th gen, which already makes everything obsolete, specially because the past 3-4 intels gen, i dont even know at this point are nothing but refresh of the refresh of the refreshed refresh bla bla bla 14nm process, so they all sucks from a innovative point of view, dont touch the 9th gen.
now, amd wise seems like their new ryzen stuff are quite the bomb, the 3900x with like 12 cores and 24 threads, pretty amazing, and although i wouldnt recommended that one, the biggest reason that i'd say wait Q2 2020 is becuz intel, finally, has to respond to amd threat instead of just breezing with their old xxx tech, plus they said they'd be coming up with some incredible shizzle, and frankly it has to be incredible if they plan to beat that 12 core 3900x, considering their best stuff is a 8core...
give it 6 months