If productivity is your main requirement & you want to upgrade in the future, you can also go for a Ryzen 7 2700. It is equivalent/slightly better w.r.t. 3600 in productivity workloads & is significantly cheaper (~17k here). Later you can also upgrade to 5000 series CPU if you select a B450 motherboard like B450 tomahawk which will supports the 5000 series. I am specifically not suggesting B550/X570 motherboard as some of them do not support 2nd Gen Ryzen for some reason.
If this doesn’t suit you & you are dead set on upgrading later, you could also go with a Ryzen 3100. It has 8 logical cores vs 6 physical cores of 3500x & should be roughly equivalent while serving you well in the short run.