^ This. Also, honestly, relying on leaks for your workflow is a recipe for disaster. I've been editing 4k footage for years and learned the hard way that waiting for the next big thing usually just stalls projects. If your screen is going black, just upgrade now. Here is how those current cards actually stack up for video editing:

• NVIDIA GeForce RTX 4080 SUPER 16GB GDDR6X: It is basically the king of efficiency right now. You get smooth timelines and really solid encoder support, which is what you need for YouTube.
• AMD Radeon RX 7900 XTX 24GB GDDR6: You get way more VRAM here, which is super nice for complex effects, but sometimes the drivers in Premiere or Resolve can be a bit more finicky than Nvidia. Don't let the hype train ruin your production schedule. Get a card that works today.

Honestly, id stop waiting. Rumors are all over the place but nothing concrete points to a 5080 super hitting shelves before November. My rig runs great with the NVIDIA GeForce RTX 4080 SUPER 16GB GDDR6X and it handles 4k edits no problem. You have 1200 saved, so just grab one now and get back to work. Dont let a black screen ruin your channel growth when you have the budget for a solid upgrade today.

Been thinking about your situation all day and honestly, waiting on a Super refresh for a professional workflow is a gamble you cant afford. In my experience, Nvidia almost never front-loads the Super lineup immediately after a flagship launch. Usually, they let the base models run the market for at least six to nine months before releasing a mid-cycle refresh. If you are hitting black screens during 4k editing, your hardware is essentially a bottleneck that is actively costing you money and time. Save yourself the headache and pick up an ASUS TUF Gaming GeForce RTX 4080 SUPER 16GB GDDR6X. It fits perfectly in your 1200 budget and the performance jump for video encoding is massive compared to older generations. I have tried many cards over the years, and for NLE workflows like Premiere or Resolve, the stability of the 40 series drivers is currently unmatched. You really dont want to gamble on a launch-day card that might have early firmware bugs when you have deadlines to meet for your channel. Get your system stable now so you can actually finish your edits instead of troubleshooting your hardware. Life is too short to be fighting with a dying machine when you could be rendering footage.