I think there's a slight chance DLSS 4 might work with rtx 4000 series if Nvidias claims of DLSS 3 being exclusive to 4000 series due to hardware limitation is actually legit.
The TOPs of a 3090 for example is 285 TOPs while the TOPs of a 4060 is 242 TOPs. And big daddy 4090 has 1321 TOPs.
So it depends on how much faster Blackwell is compared to Lovelace in TOPs as DLSS is heavily dependent on it. But Nvidia could always make it exclusive cause they are greedy.
PC Specs: CPU: 7800X3D || GPU: Strix 4090 || RAM: 32GB DDR5 6000 || Main SSD: WD 2TB SN850