You might as well ask how long is a piece of string. What minimum specs are you aiming at? (That said, I think 40k is the current ideal number for just the Player Character in an AAA game.)
I’d try finding out how many frames you get with your card. (“stat fps”, or even “stat unit” to go deeper).
Have you sorted out the LODs? There is a lot you can do to make your level more efficient, even if your frame-rate is currently acceptable.
I think one of our scenes has 11.2Million polys in view at any one time, runs @ 60FPS on a variation of hardware. I’d be more concerned with lighting / material complexity and draw calls…
If your target is mobile, forget everything above…!