We have no idea what new standards manufacturers may develop that might be incompatible with current PSUs, so futureproofing for 10yrs is a long bet. If you want to get the 4080 or 5080 in 4-5 years, along with some 20-core 5 GHz CPU that might be on the market by then, then maybe 1000w might be necessary, since the trend for power consumption shows up. That said, who knows whether there are no new standards required for these components, and considering the current PSU prices, I'd recommend you not to buy more than you need right now, you can future proof parts when they are cheap.