Gents, 
I'm running a 17 9700k on an Asus Z390-E motherboard and a RTX 2080. I, for obvious reasons, wish to upgrade to a 30 series. Does anyone know if the 30 series is compatible with my mobo? I understand that if it is and I do upgrade that I will have a bottle neck at the CPU. I'm willing to live with that until I build a new rig. In the meantime, I'd like to run the Latin VFR and other PBR heavy sceneries and the enhanced atmospherics without running out of VRAM.

Any insight would be appreciated!
 

I just installed a new 3080 12 GB card on my old z170 board with a 6700K, so your futuristic system will accept the 3000 cards just fine.  Just make sure your case has room for it. Pay close attention to overall card length and if it will fit you'll be fine. I also bought a new 850 watt PSU because the 750 that I had didn't have enough GPU 8-pin connectors (the EVGA 3080 FTW Ultra takes 3).

Your Z390 motherboard is PCIe 3.0 while the 3080 12GB is PCIe 4.0.  But you shouldn't worry much about loss of performance... see this test by TechSpot.  TL:DR scroll about 3/4 of the way thru the article to the "What we learned" section... and then enjoy your new GPU.

Late last month I built a new Z690/12900K system (not for myself) that used a new 3080 12GB.  The card performed very well (in MSFS)... strong performance and very nice visuals.  I was quite impressed with the value (only after Nvidia started slashing prices), so I ordered one for my Z390 system.  As Steve noted above, the card fits into the proper slot (#1) just fine, and I too have had no problems at all.  I also upgrade my PSU at the same time from 750W (driving my previous 2080 Super) to 1000W for the 3080 12GB.

This is why I am not upgrading this year but going for a new build next year.

Intel's Raptor Lake Reportedly Has 350W Turbo Mode, But Only on New Motherboards | Tom's Hardware (tomshardware.com)

A more balanced system to get best performance.