I would regret it after if I got myself 5800x, as I have my mindset on 5900x. Mainly it will be for gaming and some photo/video editing but ill probably keep this cpu for like 8 plus years like my old i7 3770k, so I'm not willing to compromise with 5800x.Likely after March is my understanding and then it depends on supply vs demand as to whether you'll get the MSRP or not, no guarantees. Keep an eye out for the 5800X dropping under £400 again then pull the trigger would be my advice. Unless you must have 12 cores for whatever reason. The performance for gaming and the like is almost identical between the two chips.
n0iceBlavember! I have solid news about this
A 10850k will be slower per core, and still for games you want the best single threaded performance. In fact it will be slower than a 5800X for all but the most highly threaded apps; even in those it will essentially draw even. Rocket Lake will see a decent performance uplift but that's a future upgrade like a 5900X.
I can empathise, am still waiting keenly for my New Year's 5900X purchase from OCUK, but a 10850K probably isn't a solution to your dilemma. However yes it will work with a z590 board.